Immune responses two- versus three-doses up among Dutch girls ABSTRACT

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2 CHAPTER 5 Immune responses after two- versus three-doses of HPV vaccination up to 4 ½ years post-vaccination: an observational study among routinely vaccinated Dutch girls Robine Donken Tessa M. Schurink- van t Klooster Rutger M. Schepp Fiona R.M. van der Klis Mirjam J. Knol Chris J.L.M. Meijer Hester E. de Melker Published in Journal of Infectious Diseases, 2017

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4 Immune responses two- versus three-doses up among Dutch girls ABSTRACT Background In 2014 the Netherlands switched from three- to two-doses for routine vaccination with the prophylactic bivalent human papillomavirus (HPV) vaccine. This study explored whether antibody responses are non-inferior after two- compared to three-doses in girls. Methods Girls vaccinated at twelve years of age with two- (0,6 months) or three-doses (0,1,6 months) of the bivalent HPV vaccine were identified in the vaccination registration system. Type-specific antibody concentrations and avidity against HPV16/18/31/33/45/52/58 were assessed. Analyses were stratified for time since first dose (0-2, 2-3, 3-4 and 4-4 ½ years). Non-inferiority (margin 0.5) of the twocompared to three-dose schedule in girls was examined. 5 Results Geometric mean concentrations (GMCs) for vaccine types were only non-inferior for two- compared with three-doses for HPV18 (at 2-3 years after first dose, GMC ratio 0.89, 95%CI ) For vaccine types and cross-protective types (HPV16/18/31/33/45), avidity index (AI) was non-inferior for the two- compared with three-dose schedule, except for HPV31 at 4-4 ½ years and HPV and 4-4 ½ years after first dose. Conclusion GMCs for HPV 16/18 were not non-inferior for two- compared to three- doses, except for HPV18 (at 2-3 years after first dose). However, antibody avidity for these types showed non-inferiority, independent of concentrations. 117

5 Chapter 5 INTRODUCTION Among women worldwide cervical cancer is the fourth most common cause of cancer.[1] A persistent infection with a high-risk (hr) type of the human papillomavirus (HPV) is the causative agent in the development of cervical cancer. [2] Among sexually active women approximately 80% will retrieve an HPV infection during lifetime. Most of these infections are transient, approximately 20% of women do not clear their hrhpv infection and develop a productive infection. Ultimately only 3-5% of women with a persistent infection develop a transforming infection which leads to (epi)genetic changes.[3-5] Since 2006 primary prevention against HPV-related cancers is possible by prophylactic vaccination. Three vaccines are currently available: the bivalent vaccine (Cervarix, GlaxoSmithKline) protecting against HPV16/18, the quadrivalent vaccine (Gardasil, Merck) which protects against HPV6/11/16/18 and a relatively new nonavalent vaccine (Gardasil9, Merck) which includes the same types as the quadrivalent vaccine and additionally protects against HPV31/33/45/52/58.[6, 7] All vaccines were initially licensed in a three-dose schedule. Based on available evidence, the European Medicines Agency (EMA) licensed a two-dose schedule for all three vaccines.[8-10] Licensure was based on so called immuno-bridging studies.[11, 12] These studies assumed, given the shown efficacy in young adults, that with comparable immunogenicity also efficacy would be comparable. Therefore, antibody concentrations after two-doses in pre-adolescents were compared to three-doses among young adults. However, the antibody concentrations after HPV vaccination are in general higher among younger recipients.[11, 13] On the other hand a longer protection for this age group might be needed. In addition to evaluation of antibody concentrations, other aspects of the immune response may also contribute to the success of HPV vaccination in prevention against HPV-associated cancers, such as the induction of immunological memory and the avidity of antibodies.[14, 15] The aim of this study was to compare the antibody concentrations and avidity up to 4 ½ years after the first dose within the same age group, namely young girls, who had received two- or three-doses of the prophylactic HPV16/18 L1 vaccine. 118

6 Immune responses two- versus three-doses up among Dutch girls MATERIAL AND METHODS Study design This observational study (HPV2D) was designed to evaluate the immune responses of two- (0,6 months) compared to three-doses (0,1,6 months) of vaccination with the bivalent HPV vaccine (HPV16/18) in a population-based setting. We examined non-inferiority of antibody concentrations and avidity after two- versus three-dose schedule up to 4 ½ years post-vaccination. Ethical approval The study protocol was approved by the medical ethics committee of VU University Medical Center (NL , protocol number ), Amsterdam, the Netherlands and was conducted in adherence to the Declaration of Helsinki. The study is registered in the Dutch Trial Registry (NTR 4719). Study population and procedures We used the Dutch vaccination registry Praeventis [16] to obtain a sample of girls who were routinely vaccinated between 2010 and 2013 (birth cohorts ). Analyses were stratified by cohorts, defined on by time since first dose of HPV vaccination: <2 years, 2-3 years, 3-4 years and between 4-4 ½ years. Stratification was done because previous research showed a time trend in GMC ratio for HPV18.[17] Girls who received three-doses of the bivalent HPV vaccine, the recommended schedule at that time, or who received two-doses with at least five months between doses, at the age of 12 years, were eligible. As the three-dose schedule was the standard at the time girls were vaccinated, two-dose recipients were non-compliant. To show non-inferiority of two-compared to three-doses on antibody concentrations and avidity a non-inferiority margin of 0.5 was used. This margin was based on and equal to margins used in previous studies on this topic.[17-24] Sample size calculations showed that in each dosing group and birth cohort, at least 50 girls should be included to show non-inferiority of antibody concentrations. Taken into account a response rate of 15%, we invited 2870 girls, divided equally among birth cohorts and schedules, to participate in the study. Girls and their parents received an invitation letter supplemented by a consent form in September If both the girl and her parent(s) or guard(ians) had provided written consent the girl received a research package at home, including a link to an online questionnaire and materials for capillary blood drawing. Capillary blood 5 119

7 Chapter 5 samples were obtained by the use of protein saver cards (Whatman 903 Protein Saver Card, GE Healthcare, Cardiff, United Kingdom). After participants had completed the questionnaire and the blood drawing, they received an incentive of 25,-. Serological evaluation All serological analysis was performed in a blinded manner. The protein saver cards containing the dry blood spot (DBS) samples were stored at -20 C until analysis. A previous validation pilot (unpublished) showed that for all seven examined serotypes the correlation between DBS and conventional serum measurements was high (R , correlation coefficients ). A single small (3 mm) DBS punch from every sample was collected in 250µl assay buffer (phosphate buffered saline (PBS), 1% Bovine Serum Albumine (BSA), 0.2% Tween20) and incubated overnight at 4 C on a shaking platform, resulting in a 200 fold serum sample dilution. All samples, diluted 200 and 5000 fold in assay buffer, were determined simultaneously within one assay run using an HPV multiplex assay as previously described by Scherpenisse et al.[25] Hereby virus-like particles (VLPs), kindly donated by GSK were coupled to distinct fluorescent microspheres (Luminex Corporation, Austin, USA) and HPV specific IgG antibodies were analysed using a Bioplex system 200 with Bioplex software (Bio-Rad Laboratories, Hercules, CA). For each analyte, median fluorescent intensity (MFI) was converted to Luminex Units/ml (LU/ml) using a twofold serial dilution of a reference standard (IVIG, lot LE12H227AF, Baxter) and interpolating the MFI data through a 5-parameter curve-fitting algorithm. Cutoffs for seropositivity had been previously determined at 9, 13, 27, 11, 19, 14 and 31 LU/ml for HPV16, 18, 31, 33, 45, 52 and 58, respectively.[25] Evaluation of antibody avidity The avidity of IgG specific antibodies was determined by a modification of the VLP multiplex immunoassay as described earlier by Scherpenisse et al.[26] In short, sera were diluted to a HPV antibody concentration of LU/ml and incubated at room temperature for one hour with VLP conjugated beads. After three washes, 50 µl of a 2.5 M ammonium thiocyanate solution (NH4SCN; Sigma-Aldricht, St.Louis, Missouri, USA) in PBS was added and incubated 10 minutes at room temperature, followed by three washes with PBS. Residual bound antibodies were measured. The avidity index (AI) was calculated as the percentage 120

8 Immune responses two- versus three-doses up among Dutch girls IgG antibodies still binding after being eluted with the thiocyanate solution in comparison with concentrations after addition of (only) PBS (set at 100%). The AI for for two- and three-doses was assessed in a subset of approximately 230 (range per serotype) randomly selected samples; per serotype. To minimize assay variability, assays were performed in one run and by one lab technician (RS). Statistical analysis Differences between participants receiving two- or three-doses in sociodemographic characteristics were compared using Fisher s Exact test, for the differences in ages and time since vaccination a two sample median test was used. IgG geometric mean concentrations (GMCs) for HPV type-specific antibodies were calculated. We calculated the GMC ratio with corresponding 95% confidence interval (CI) for the two- versus three-doses, non-inferiority was concluded if the 95% CI did not include the margin of 0.5. To assess non-inferiority for the geometric mean AI, the ratio of two- divided three-doses and corresponding 95% CI was calculated and also a margin of 0.5 was used here. Data analysis was performed using SAS software package 9.3 (SAS Institute INC., Cary, NC, USA). 5 Sensitivity analysis We crosschecked the data on vaccination status obtained from the vaccination registry with that self-reported in the questionnaire. We selected those participants with consistent information regarding vaccination status from these two sources. Next, we calculated the GMC ratios for HPV16 and HPV18 comparing these groups with respectively two- and three-doses. We did the same for the antibody avidity index. RESULTS Socio-demographic characteristics In total 466 girls (response rate 16.2%) participated in the study, of which 37 participants did not complete the questionnaire (19 had received three- and 18 had received two-doses). For participants without a questionnaire only age and number of doses was known. Of participants who filled out the questionnaire, 298 participants had received three- and 131 had received two-doses. Not for all cohorts the required sample size was reached, unfortunately in these birth cohorts 121

9 Chapter 5 Table 1. Age and Time Since The First Dose in Participants Stratified by Dosing Schedule a. 0-2 Years (n=145) 2-3 Years (n=118) 3-4 Years (n=106) 4-4 ½ Years (n=97) 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value (n=89) (n=56) (n=81) (n=37) (n=73) (n=33) (n=74) (n=23) Age in years, median (range) 14 (13-15) 14 (13-15) (14-16) 15 (14-16) (15-17) 16 (15-17) (16-17) 17 (16-17) 0.83 Time since first dose, median (range) 562 ( ) ( ) ( ) 915 ( ) ( ) 1265 ( ) 0.03* ( ) 1624 ( ) 0.18 a Data in Table 1 represent all participants. Table 2. Sociodemographic Characteristics of Participants Stratified by Dosing Schedule a. Characteristic, No (%) 0-2 Years (n=136) 2-3 Years (n=108) 3-4 Years (n=97) 4-4 ½ Years (n=90) 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value (n=83) (n=53) (n=77) (n=29) (n=68) (n=29) (n=70) (n=20) Current educational level Low 14 (17%) 12 (23%) (14%) 9 (31%) (13%) 3 (10%) (6%) 0 (0%) 0.45 Middle 21 (25%) 13(25%) 22 (29%) 6 (21%) 24 (35%) 12 (41%) 32 (46%) 7 (35%) High 48 (58%) 27 (51%) 43 (56%) 14 (48%) 35 (51%) 14 (48%) 34 (49%) 13 (65%) Unknown 0 (0%) 1 (2%) 1 (1%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) Country of birth Netherlands 79 (95%) 49 (94%) (94%) 26 (90%) (100%) 28 (97%) (97%) 17 (85%) 0.03 Europe 1 (1%) 1 (2%) 4 (5%) 1 (3%) 0 (0%) 1 (3%) 2 (3%) 1 (5%) Other 3 (4%) 2 (4%) 1 (1%) 2 (7%) 0 (0%) 0 (0%) 0 (0%) 5 (10%) Country of birth mother Netherlands 80 (96%) 45 (85%) (95%) 22 (76%) < (96%) 22 (76%) (90%) 17 (85%) 0.70 Europe 1 (1%) 2 (4%) 3 (4%) 2 (7%) 1 (1%) 2 (7%) 3 (4%) 1 (5%) Other 2 (2%) 6 (11%) 1 (1%) 5 (17%) 2 (3%) 4 (14%) 4 (6%) 2 (10%) Unknown 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 1 (3%) 0 (0%) 0 (0%) 122

10 Immune responses two- versus three-doses up among Dutch girls Table 2. Continued. 0-2 Years (n=136) 2-3 Years (n=108) 3-4 Years (n=97) 4-4 ½ Years (n=90) 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value 3 Doses 2 Doses p-value (n=83) (n=53) (n=77) (n=29) (n=68) (n=29) (n=70) (n=20) Characteristic, No (%) Country of birth father Netherlands 79 (95%) 45 (87%) (97%) 18 (62%) < (97%) 22 (76%) < (93%) 15 (75%) 0.03 Europe 1 (1%) 1 (2%) 2 (3%) 2 (7%) 1 (1%) 1 (3%) 2 (3%) 0 (0%) Other 3 (4%) 6 (12%) 0 (0%) 8 (28%) 1 (1%) 5 (17%) 3 (4%) 5 (25%) Unknown 0 (0%) 0 (0%) 0 (0%) 1 (3%) 0 (0%) 1 (3%) 0 (0%) 0 (0%) Oral anticonceptive use Current user 4 (5%) 4 (8%) (13%) 9 (31%) (40%) 14 (48%) (73%) 13 (65%) 0.69 Past user 2 (2%) 1 (2%) 2 (3%) 0 (0%) 1 (1%) 2 (7%) 5 (7%) 1 (5%) No 77 (93%) 48 (91%) 65 (84%) 20 (69%) 40 (59%) 13 (45%) 14 (20%) 6 (30%) Ever had seks Never 82 (99%) 51 (96%) (92%) 26 (90%) (84%) 19 (66%) (53%) 12 (60%) 0.62 Yes 1 (1%) 2 (4%) 6 (8%) 2 (7%) 11 (16%) 10 (35%) 33 (47%) 8 (40%) Don t know 0 (0%) 0 (0%) 0 (0%) 1 (3%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) Age at sexual debut (13-17) (12-16) 15 (15-15) (13-16) 14.5 (14-15) (13-15) 14 (14-14) 15 (15-15) Median (range) Immuuncompromised No 82 (99%) 53 (100%) (100%) 29 (100%) (100%) 29 (100%) (100%) 20 (100%) 1.00 Yes 1 (1%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) Don t Know 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) Immuunsupressive medication No 79 (95%) 53 (100%) (96%) 29 (100%) (90%) 29 (100%) (96%) 19 (95%) 1.00 Yes 2 (2%) 0 (0%) 3 (4%) 0 (0%) 4 (6%) 0 (0%) 3 (4%) 1 (5%) Don t Know 2 (2%) 0 (0%) 0 (0%) 0 (0%) 3 (4%) 0 (0%) 0 (0%) 0 (0%) Had menarche Yes 72 (87%) 46 (87%) (95%) 27 (93%) (99%) 28 (97%) (100%) 20 (100%) 1.00 No 11 (13%) 7 (13%) 4 (5%) 2 (7%) 1 (1%) 1 (3%) 0 (0%) 0 (0%) a Data in Table 2 represent only participants who filled out the questionnaire

11 Chapter 5 no more two-dose recipients were available from the vaccination registry which could be invited. Time since the first dose was comparable between different dosing schedules for the cohorts who had received the first dose between 2-3 years ago and 4-4 ½ years ago.(table 1) For the cohorts shorter than 2 years after the first dose and in the cohort who had received the first dose 3 to 4 years ago, the median time span since first dose was smaller in the two-dose group. The median time between the doses for two-doses was 189 days with a range from 151 to 752. For three-doses the median time between first and second dose was 34 days with a range from 23 to 218 days, and between second and third dose was 161 days with a range from 119 to 845. We did not observe a correlation between time between doses and antibody concentrations (data not shown). Participants who had received two-doses did not differ significantly from those who had received three-doses in age, current educational level, oral anticonceptive use, whether they had sex, age sexual debut, whether they were immunocompromised or used immune suppressive medication and had menarche. Most participants were born in the Netherlands. (Table 2) Geometric Mean Concentrations For the vaccine types HPV16/18, GMCs after two- were lower than after threedoses.(figure 1) Non-inferiority was only concluded at 2-3 years after the first dose for HPV18. For non-vaccine-types, GMCs of the two-dose schedule were also lower than for the three-dose schedule, except for HPV33/52/58 at 2-3 years and for HPV52 at 3-4 years after the first dose. For the examined HPV-types noninferiority was only concluded at 2-3 after the first dose for HPV31 and 3-4 years for HPV52. The difference between two- and three-doses was smallest at 2-3 years (GMC ratio closest to one) after the first dose for all examined HPV-types. For vaccine types HPV16/18 it seems that the differences are larger up to <2 years after vaccination, becomes smaller at 2-3 years, and there after increase again.(table 3) 124

12 Immune responses two- versus three-doses up among Dutch girls 5 Figure 1. Geometric mean concentrations (GMCs) (top) and GMC ratios (bottom) for human papillomavirus (HPV) types included in the vaccine. Ratios represent GMC for two-dose schedule divided by GMC for three-dose schedule. Dashed lines in the right panel represent noninferiority margin of 0.5. Avidity There were no significant differences in socio-demographics between participants in whom avidity was examined and in whom avidity was not determined, except for country of birth of the mother (data not shown). In participants in whom avidity was examined, the country of birth of the mother was more often outside Europe. In general, geometric mean AI were higher for vaccine types than for the other HPV types measured.(figure 2) For HPV16, the geometric mean AI varied between 74%-77% for three- and 67%-80% for two-doses. For HPV18 this was respectively 63%-67% and 54%-79%. 125

13 Chapter 5 Table 3. Geometric Mean Concentrations (GMC) for IgG antibodies against seven HPV types among girls who received a two- or three-dose schedule of HPV vaccination with the first dose up to 4 ½ years before sampling. GMC ratio and corresponding 95% confidence interval (CI) for two divided by three-doses. If the 95% CI of the GMC ratio is greater than 0.5, non-inferiority can be concluded. 2 Doses 3 Doses GMC ratio Type GMC (95% CI) GMC (95% CI) Ratio (95% CI) 0-2 Years since vaccination HPV ( ) ( ) 0.35 ( ) HPV ( ) ( ) 0.55 ( ) HPV ( ) 46.1 ( ) 0.40 ( ) HPV ( ) 22.2 ( ) 0.55 ( ) HPV ( ) 85.6 ( ) 0.58 ( ) HPV ( ) 22.9 ( ) 0.61 ( ) HPV ( ) 46.5 ( ) 0.47 ( ) 2-3 Years since vaccination HPV ( ) ( ) 0.73 ( ) HPV ( ) ( ) 0.89 ( )* HPV ( ) 29.7 ( ) 0.82 ( )* HPV ( ) 15.0 ( ) 1.14 ( )* HPV ( ) 47.5 ( ) 0.96 ( )* HPV ( ) 16.8 ( ) 1.11 ( )* HPV ( ) 31.8 ( ) 1.09 ( )* 3-4 Years since vaccination HPV ( ) ( ) 0.63 ( ) HPV ( ) ( ) 0.79 ( ) HPV ( ) 33.8 ( ) 0.59 ( ) HPV ( ) 40.9 ( ) 0.23 ( ) HPV ( ) 38.5 ( ) 0.27 ( ) HPV ( ) 19.5 ( ) 1.46 ( )* HPV ( ) 37.3 ( ) 0.63 ( ) 4-4 1/2 Years since Vaccination HPV ( ) ( ) 0.51 ( ) HPV ( ) ( ) 0.50 ( ) HPV ( ) 30.6 ( ) 0.51 ( ) HPV ( ) 15.5 ( ) 0.57 ( ) HPV ( ) 42.9 ( ) 0.51 ( ) HPV ( ) 18.4 ( ) 0.54 ( ) HPV ( ) 31.2 ( ) 0.54 ( ) * = Non-inferior (lower boundary 95% CI > 0.5) For vaccine types HPV16/18 the geometric mean AI was non-inferior up to 4 ½ years post-vaccination for two-compared with three-doses. Also at most time-points non-inferiority for cross-protective types HPV31/33/45 could be concluded, except for HPV31 at 4-4 ½ years and HPV33 at 3-4 and 4-4 ½ years post-vaccination.(table 4) 126

14 Immune responses two- versus three-doses up among Dutch girls 5 Figure 2. Avidity Index (AI) for vaccine and cross-protective types up till four years since first dose after the two- (2D) and three-dose (3D) schedule. The black line indicates the median antibody AI for the respective group. Sensitivity analysis Among recipients with respectively two- or three-doses documented in the vaccination registry, in 70.4% and 80.4% the self-reported vaccination status was consistent with the vaccination registry. Restricting the analysis to those participants who reported similar number of doses in the questionnaire as documented in the vaccination registry, showed that the difference in GMCs for HPV16 and HPV18 between dosing schedules were larger. For none of the time points non-inferiority could be concluded.(appendix 1) Additionally we also analyzed the antibody avidity using this reclassification. The number of participants that participants that had received two-doses based on the vaccination registry and self-reported vaccination status between 4-4 ½ years after the first dose was very small (n=2) and resulted in very broad CIs around the geometric mean AI and corresponding ratio. All other time points showed non-inferior antibody avidity for HPV16 and HPV18, which was in line with findings based on the vaccination registry only (Appendix 2). 127

15 Chapter 5 Table 4. Geometric Mean AI Ratios after a two- versus three-dose schedule. 2 Doses 3 Doses GM avidity index Type GM Index (95% CI) GM Index (95% CI) ratio (95% CI) 0-2 Years since vaccination HPV16 69% (64%-74%) 76% (73%-79%) 0.91 ( )* HPV18 60% (51%-71%) 63% (56%-71%) 0.95 ( )* HPV31 20% (15%-27%) 22% (18%-27%) 0.93 ( )* HPV33 31% (24%-40%) 32% (28%-38%) 0.96 ( )* HPV45 21% (17%-26%) 27% (23%-32%) 0.76 ( )* HPV52 17% (14%-22%) 18% (14%-22%) 0.95 ( )* HPV58 17% (13%-23%) 20% (13%-23%) 0.87 ( )* 2-3 Years since vaccination HPV16 69% (64%-76%) 74% (72%-77%) 0.93 ( )* HPV18 65% (58%-73%) 67% (61%-74%) 0.97 ( )* HPV31 26% (20%-33%) 24% (19%-29%) 1.09 ( )* HPV33 36% (23%-55%) 40% (35%-46%) 0.90 ( )* HPV45 27% (22%-36%) 27% (23%-32%) 0.99 ( )* HPV52 15% (12%-19%) 18% (15%-22%) 0.85 ( )* HPV58 15% (12%-19%) 19% (15%-24%) 0.79 ( ) 3-4 Years since vaccination HPV16 80% (73%-86%) 77% (74%-80%) 1.04 ( )* HPV18 79% (59%-74%) 63% (56%-72%) 1.25 ( )* HPV31 65% (59%-73%) 22% (18%-26%) 3.00 ( )* HPV33 15% (11%-20%) 34% (29%-40%) 0.45 ( ) HPV45 32% (22%-45%) 29% (25%-34%) 1.07 ( )* HPV52 26% (21%-31%) 15% (13%-18%) 1.67 ( )* HPV58 11% (8%-16%) 20% (16%-25%) 0.57 ( ) 4-4 1/2 Years since Vaccination HPV16 67% (62%-73%) 74% (70%-77%) 0.91 ( )* HPV18 54% (39%-74%) 66% (59%-76%) 0.81 ( )* HPV31 16% (8%-31%) 23% (18%-28%) 0.69 ( ) HPV33 30% (13%-75%) 29% (23%-38%) 1.03 ( ) HPV45 33% (18%-60%) 30% (26%-36%) 1.09 ( )* HPV52 16% (10%-24%) 17% (14%-20%) 0.92 ( )* HPV58 16% (6%-45%) 18% (15%-23%) 0.88 ( ) * = Non-inferior (lower boundary 95% CI > 0.5) DISCUSSION This study aimed to compare the quantity and quality of antibody responses up to 4 ½ years after the first dose in routinely vaccinated young girls who had received two- or three-doses of HPV vaccination, by measuring antibody concentration and avidity. Most studies on this topic so far have been clinical trials and/or compared 128

16 Immune responses two- versus three-doses up among Dutch girls the antibody concentrations in girls of two- to three-doses in young adults. We found that GMCs for vaccine and cross-protective types after two-doses were only non-inferior to three-doses at 2-3 years post-vaccination for vaccine type HPV18 and cross-protective types HPV31/33/45. However, for HPV16/18 at all time points and for cross-protecting types AI at almost all time point showed noninferiority. The observed GMCs after both two- and three-doses are high. In accordance to previous studies comparing two- with three-doses within the same age, the antibody concentrations after three-doses were in general higher.[19, 22] In a population-based study, Lazcano-Ponce et al. showed non-inferior estimates for HPV16/18 up to 21 months after the first dose (GMT ratio for three- vs twodoses % CI and % CI , respectively) comparing girls who had received three- or two-doses at 9-10 years of age.[19] In contrast, for girls 9-14 years old, Romanowski et al. did not show non-inferiority of two-doses at 7 and 24 months after the first dose for HPV16 and at 24 months for HPV18. [22] Recently, a study comparing immunogenicity and effectiveness after different dosing schedules of the quadrivalent vaccine also showed non-inferior antibody levels up to 48 months within the same age group.[23] By comparing the antibody concentrations over time in this study it should be taken into account that measurements at different time points were performed in different participants, given the design of this study. 5 Although we found some differences in the level of antibody concentrations between two- and three-doses, implication of these differences is unknown. Despite that registration of the two-dose schedule was mainly based on findings on antibody concentrations, a threshold of protection for HPV is unknown.[8, 9] Furthermore, besides antibody concentrations, also other immune factors might be of influence on protection and impact of HPV vaccination.[14] The geometric mean AI ratios show a more or less stable pattern over time. Compared to the GMC ratios, the AI ratios are closer to one, meaning less difference between the schedules. Hence, two-doses generates geometric mean AI which are non-inferior to those generated by the three-doses for both vaccine and cross-protective types. This is in line with data from Boxus et al. who observed no differences in avidity between two- or three-doses of the quadrivalent vaccine (girls 129

17 Chapter years of age) for HPV16/18 up to month 48.[27] Also for the quadrivalent HPV vaccine the AI was shown to be non-inferior in girls 10 till 18 years of age. [23] Collectively these data indicate that although the level of antibodies between dosing schedules may differ, the AI remains similar two- or three-doses of HPV vaccine are given. [27-30] In this context it is interesting that Scherpenisse et al. suggested that in addition to antibody concentration, AI levels could be used to differentiate HPV protective from non-protective antibodies, and could therefore serve as possible immune surrogate.[26] Avidity is an indicator of antibody quality. Low concentrations of high avidity antibodies might be able to provide sufficient protection. On the other hand, with higher antibody concentrations, the total number of highly avid antibodies becomes larger. In absence of a correlate of protection, the exact mechanism is difficult to predict. However, Safaeian et al. showed that HPV31 cases were more likely to have lower HPV16 antibody avidity. [31] This study focused on immunological aspects after different doses of HPV vaccine. Effectiveness was not taken into account. At this time, several studies have looked into efficacy after two-dose schedules, most of them were post-hoc analyses which were not powered for this comparison, in groups who had accidentally received alternate dosage schedules and where mostly the second dose was not given in the recommended time window. No significant differences were observed between different dosing schedules for vaccine types, however only three-doses and twodoses given six months apart showed significant efficacy against cross-protective types HPV31/33/45.[32] A Scottish study examining HPV prevalence found no significant differences between different schedules for vaccine types, however a significant reduction for cross-protective types HPV31/33/45 was only shown after three-doses.[33] To our knowledge this study is the first to determine antibody concentrations and antibody avidity for different dosing schedules in young girls against crossprotective HPV-vaccination types up to 4 ½ years after the first dose for the bivalent vaccine. To minimize assay variability for the avidity measurement, all assays were performed in one run by the same technician. We found some differences between the vaccination status as reported in the vaccination registry and the self-reported vaccination status. Although previous studies have shown that the vaccination status from a registry might be more reliable than the self-reported vaccination 130

18 Immune responses two- versus three-doses up among Dutch girls status [34, 35], we explored the influence of possible registration errors in sensitivity analyses. These analyses strengthen our previous findings. Limitations of this study are the lack of efficacy data and possibly suboptimal power as the ideal sample size for both schedules could not always be realized for all cohorts. Additionally two-dose girls were originally eligible for three-doses, although had received the doses with at least five months apart. CONCLUSION Our data show that while differences in antibody concentrations exist between two- and three-doses among young girls, the antibody avidity does not differ. However, until a correlate of protection has been detected, long-term evaluation of the protective effect of reduced dosing schedules against cervical intraepithelial neoplasia lesions (and intermediate endpoints) in studies designed and powered for this issue are important

19 Chapter 5 REFERENCES 1. World Health Organization. Human papillomavirus (HPV) and cervical cancer, Fact sheet. Available at: factsheets/fs380/en/. 2. Walboomers JM, Jacobs MV, Manos MM, et al. Human papillomavirus is a necessary cause of invasive cervical cancer worldwide. The Journal of pathology 1999; 189: Koutsky LA, Holmes KK, Critchlow CW, et al. A cohort study of the risk of cervical intraepithelial neoplasia grade 2 or 3 in relation to papillomavirus infection. The New England journal of medicine 1992; 327: Winer RL, Kiviat NB, Hughes JP, et al. Development and duration of human papillomavirus lesions, after initial infection. The Journal of infectious diseases 2005; 191: Woodman CB, Collins SI, Young LS. The natural history of cervical HPV infection: unresolved issues. Nature reviews Cancer 2007; 7: Joura EA, Giuliano AR, Iversen OE, et al. A 9-valent HPV vaccine against infection and intraepithelial neoplasia in women. The New England journal of medicine 2015; 372: Lehtinen M, Dillner J. Clinical trials of human papillomavirus vaccines and beyond. Nature reviews Clinical oncology 2013; 10: European Medicines Agency (EMA). Assessment report Cervarix Available at: document_library/epar_-_assessment_ Report_-_Variation/human/000721/WC pdf. 9. European Medicines Agency (EMA). Assessment report Gardasil Available at: document_library/epar_-_assessment_ Report_-_Variation/human/000703/WC pdf 10. Murray S. CHMP recommends Sanofi s twodose schedule HPV vaccine. Available at: chmp-recommends-sanofi-s-two-doseschedule-hpv-vaccine. Accessed Pedersen C, Petaja T, Strauss G, et al. Immunization of early adolescent females with human papillomavirus type 16 and 18 L1 virus-like particle vaccine containing AS04 adjuvant. The Journal of adolescent health : official publication of the Society for Adolescent Medicine 2007; 40: Reisinger KS, Block SL, Lazcano-Ponce E, et al. Safety and persistent immunogenicity of a quadrivalent human papillomavirus types 6, 11, 16, 18 L1 virus-like particle vaccine in preadolescents and adolescents: a randomized controlled trial. The Pediatric infectious disease journal 2007; 26: Block SL, Nolan T, Sattler C, et al. Comparison of the immunogenicity and reactogenicity of a prophylactic quadrivalent human papillomavirus (types 6, 11, 16, and 18) L1 virus-like particle vaccine in male and female adolescents and young adult women. Pediatrics 2006; 118: Stanley MA, Sudenga SL, Giuliano AR. Alternative dosage schedules with HPV virus-like particle vaccines. Expert review of vaccines 2014; 13: Goldblatt D, Vaz AR, Miller E. Antibody avidity as a surrogate marker of successful priming by Haemophilus influenzae type b conjugate vaccines following infant immunization. The Journal of infectious diseases 1998; 177: van Lier A, Oomen P, de Hoogh P, et al. Praeventis, the immunisation register of the Netherlands: a tool to evaluate the National Immunisation Programme. Euro surveillance : 2012; Donken R, Knol MJ, Bogaards JA, van der Klis FR, Meijer CJ, de Melker HE. Inconclusive evidence for non-inferior immunogenicity of two- compared with three-dose HPV immunization schedules in preadolescent girls: A systematic review and meta-analysis. The Journal of infection Donken R, de Melker HE, Rots NY, Berbers G, Knol MJ. Comparing vaccines: a systematic review of the use of the non-inferiority margin in vaccine trials. Vaccine 2015; 33: Lazcano-Ponce E, Stanley M, Munoz N, et al. Overcoming barriers to HPV vaccination: non-inferiority of antibody response to human papillomavirus 16/18 vaccine in adolescents vaccinated with a two-dose vs. a three-dose schedule at 21 months. Vaccine 2014; 32: Romanowski B, Schwarz TF, Ferguson L, et al. Sustained immunogenicity of the HPV-16/18 AS04-adjuvanted vaccine administered as a two-dose schedule in adolescent girls: Fiveyear clinical data and modeling predictions from a randomized study. Human vaccines & immunotherapeutics 2016; 12:

20 Immune responses two- versus three-doses up among Dutch girls 21. Romanowski B, Schwarz TF, Ferguson LM, et al. Immune response to the HPV-16/18 AS04-adjuvanted vaccine administered as a 2-dose or 3-dose schedule up to 4 years after vaccination: results from a randomized study. Human vaccines & immunotherapeutics 2014; 10: Romanowski B, Schwarz TF, Ferguson LM, et al. Immunogenicity and safety of the HPV- 16/18 AS04-adjuvanted vaccine administered as a 2-dose schedule compared with the licensed 3-dose schedule: results from a randomized study. Human vaccines 2011; 7: Sankaranarayanan R, Prabhu PR, Pawlita M, et al. Immunogenicity and HPV infection after one, two, and three-doses of quadrivalent HPV vaccine in girls in India: a multicentre prospective cohort study. The Lancet Oncology Dobson SR, McNeil S, Dionne M, et al. Immunogenicity of 2 doses of HPV vaccine in younger adolescents vs 3 doses in young women: a randomized clinical trial. JAMA 2013; 309: Scherpenisse M, Mollers M, Schepp RM, et al. Seroprevalence of seven high-risk HPV types in The Netherlands. Vaccine 2012; 30: Scherpenisse M, Schepp RM, Mollers M, Meijer CJ, Berbers GA, van der Klis FR. Characteristics of HPV-specific antibody responses induced by infection and vaccination: cross-reactivity, neutralizing activity, avidity and IgG subclasses. PloS one 2013; 8:e Boxus M, Lockman L, Fochesato M, Lorin C, Thomas F, Giannini SL. Antibody avidity measurements in recipients of Cervarix vaccine following a two-dose schedule or a three-dose schedule. Vaccine 2014; 32: Giannini SL, Hanon E, Moris P, et al. Enhanced humoral and memory B cellular immunity using HPV16/18 L1 VLP vaccine formulated with the MPL/aluminium salt combination (AS04) compared to aluminium salt only. Vaccine 2006; 24: Kemp TJ, Garcia-Pineres A, Falk RT, et al. Evaluation of systemic and mucosal anti- HPV16 and anti-hpv18 antibody responses from vaccinated women. Vaccine 2008; 26: Kemp TJ, Safaeian M, Hildesheim A, et al. Kinetic and HPV infection effects on crosstype neutralizing antibody and avidity responses induced by Cervarix((R)). Vaccine 2012; 31: Safaeian M, Kemp TJ, Pan DY, et al. Crossprotective vaccine efficacy of the bivalent HPV vaccine against HPV31 is associated with humoral immune responses: results from the Costa Rica Vaccine Trial. Human vaccines & immunotherapeutics 2013; 9: Kreimer AR, Struyf F, Del Rosario-Raymundo MR, et al. Efficacy of fewer than three-doses of an HPV-16/18 AS04-adjuvanted vaccine: combined analysis of data from the Costa Rica Vaccine and PATRICIA Trials. The Lancet Oncology 2015; 16: Kavanagh K, Pollock KG, Potts A, et al. Introduction and sustained high coverage of the HPV bivalent vaccine leads to a reduction in prevalence of HPV 16/18 and closely related HPV types. British journal of cancer 2014; 110: Attanasio L, McAlpine D. Accuracy of parental reports of children s HPV vaccine status: implications for estimates of disparities, Public Health Rep 2014; 129: Stupiansky NW, Zimet GD, Cummings T, Fortenberry JD, Shew M. Accuracy of selfreported human papillomavirus vaccine receipt among adolescent girls and their mothers. The Journal of adolescent health : 2012; 50:

21 Chapter 5 APPENDICES Appendix 1 Sensitivity analysis Geometric Mean Concentrations. GMC ratio and corresponding 95% confidence interval (CI) for recipients of two- (based on self-reported and registered vaccination status) divided by three-doses (based on self-reported and registered vaccination status). If the 95% CI of the GMC ratio is greater than 0.5, non-inferiority can be concluded. 2 Doses 3 Doses GMC ratio Type GMC (95% CI) GMC (95% CI) Ratio (95% CI) 0-2 Years since vaccination HPV ( ) ( ) 0.33 ( ) HPV ( ) ( ) 0.51 ( ) 2-3 Years since vaccination HPV ( ) ( ) 0.58 ( ) HPV ( ) ( ) 0.71 ( ) 3-4 Years since vaccination HPV ( ) ( ) 0.49 ( ) HPV ( ) ( ) 0.61 ( ) 4-4 ½ Years since Vaccination HPV ( ) ( ) 0.44 ( ) HPV ( ) ( ) 0.58 ( ) * = Non-inferior (lower boundary 95% CI > 0.5) 134

22 Immune responses two- versus three-doses up among Dutch girls Appendix 2 Sensitivity analysis Geometric Mean Antibody Avidity Index. Geometric Mean AI Ratio represents the geometric mean AI after a two-dose schedule divided by the three-dose schedule. Non-inferiority could be concluded if the 95% CI is greater than the non-inferiority margin of Doses 3 Doses GM avidity index Type GM Index (95% CI) GM Index (95% CI) ratio (95% CI) 0-2 Years since vaccination HPV16 69 (64-75) 77 (74-81) 0.90 ( )* HPV18 62 (50-73) 62 (54-72) 2-3 Years since vaccination HPV16 64 (55-74) 74 (71-77) 0.87 ( )* HPV18 60 (49-72) 67 (60-76) 3-4 Years since vaccination HPV16 82 (70-96) 77 (74-81) 1.07 ( )* HPV18 76 (64-88) 67 (59-77) 4-4 ½ Years since Vaccination HPV16 # 67 (34->100) 75 (71-80) 0.89 ( ) HPV18 # 50 (0->100) 65 (56-76) 0.78 ( ) * = Non-inferior (lower boundary 95% CI > 0.5) # = Small subgroup (N=2) 5 135