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Evaluation of rabies immunogenicity and tolerability following a purified chick embryo cell rabies vaccine administered concomitantly with a Japanese encephalitis vaccine
Travel Medicine and Infectious Disease (2015) 13, 241e250
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevierhealth.com/journals/tmid
Evaluation of rabies immunogenicity and tolerability following a purified chick embryo cell rabies vaccine administered concomitantly with a Japanese encephalitis vaccine* Tomas Jelinek a, Jakob P. Cramer b, Sebastian Dieckmann c, Christoph Hatz d, Maria Paulke-Korinek e, Martin Alberer f, Emil C. Reisinger g, Marco Costantini h, Dieter Gniel i, Dietrich Bosse i, Maria Lattanzi h,* a
Berlin Center for Travel and Tropical Medicine, Berlin, Germany Bernhard Nocht Institute for Tropical Medicine, Department of Clinical Research/University Medical Center Hamburg-Eppendorf, Department of Internal Medicine, Section Tropical Medicine, Hamburg, Germany c Institute of Tropical Medicine and International Health, Charite´-Universitaetsmedizin Berlin, Germany d Institute of Social and Preventive Medicine, University of Zu¨rich, Switzerland e Institute of Specific Prophylaxis and Tropical Medicine, Medical University Vienna, Austria f Department of Infectious Diseases and Tropical Medicine, University of Munich, Munich, Germany g Department of Tropical Medicine and Infectious Diseases, University of Rostock Medical School, Rostock, Germany h Novartis Vaccines and Diagnostics Srl e a GSK company, Siena, Italy i Novartis Vaccines and Diagnostics Srl e a GSK company, Marburg, Germany b
Received 3 November 2014; received in revised form 30 April 2015; accepted 3 May 2015
Available online 18 May 2015
Abbreviations: GMC, geometric mean concentrations; JE, Japanese encephalitis; RVNA, rabies virus neutralizing antibody. * This study has been presented at the Northern European Conference on Travel Medicine (NECTM), June 5e8, 2014, Bergen, Norway. * Corresponding author. Novartis Vaccines and Diagnostics Srl e a GSK company, Via Fiorentina, 1, 53100 Siena, Italy. Tel.: þ39 0577245273. E-mail address: [email protected] (M. Lattanzi). http://dx.doi.org/10.1016/j.tmaid.2015.05.008 1477-8939/ª 2015 Elsevier Ltd. All rights reserved.
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KEYWORDS Rabies; Japanese encephalitis; Vaccination
T. Jelinek et al.
Summary Background: For individuals traveling at short notice to rabies and Japanese encephalitis (JE) endemic countries, concomitant administration of travel vaccines within a short period is often required. Methods: The aim of this study was to determine whether an accelerated (one-week: Days 1 e8) pre-exposure rabies (Rabipur , Novartis Vaccines) vaccination regimen administered concomitantly with a Japanese encephalitis (JE) vaccination (Ixiaro, Valneva) regimen, is non-inferior to the standard (four-week: Days 1, 8, 29) rabies regimen administered alone or concomitantly with the JE vaccine. Healthy adults (18 to 65 years) were randomized into Rabies þ JE-Standard, Rabies þ JE-Accelerated, Rabies-Standard and JE-Standard groups. Relative immunogenicity for rabies in each regimen was assessed using the rapid fluorescent focus inhibition test. Safety was evaluated up to and including Day 57. Results: Non-inferior immunogenicity for rabies was established between the Rabies þ JEAccelerated group compared to both the Rabies-Standard and Rabies þ JE-Standard groups; as well as between the Rabies þ JE-Standard regimen and the Rabies-Standard regimen. By Day 57, adequate neutralizing levels were achieved by 97e100% of subjects across all groups. Adverse events (AEs) were comparable for all groups. Conclusions: An accelerated pre-exposure rabies and JE vaccination regimen is non-inferior to the standard four-week rabies regimen and may thus provide a more convenient regimen for individuals traveling to endemic countries at short notice. NCT01662440. ª 2015 Elsevier Ltd. All rights reserved.
1. Introduction Rabies and Japanese encephalitis (JE) are serious diseases that are of concern to individuals traveling to countries where these conditions are prevalent. Prophylactic vaccinations against these diseases are thus recommended, particularly for prolonged trips and/or if access to medical care will be limited [1,2]. Rabies especially is a problem across large parts of Africa, India and Asia, where the incidence of injuries to travelers caused by potentially rabid animals is estimated to be approximately 0.4% per month of stay [3]. Pre-exposure rabies vaccination helps provide effective protection by inducing immunological memory. The regimen consists of three full intramuscular doses of a cell-culture based vaccine administered over a three to four week period [4]. The World Health Organization (WHO) International Travel and Health [4] recommends that travelers who are planning extensive outdoor exposure in endemic countries (e.g. camping, hiking etc.), particularly during the rainy season receive adequate immunization against JE prior to travel. Primary JE immunization consists of two intramuscular doses with an inactivated Vero cell-derived JE vaccine, administered four weeks apart [4]. In many countries in Asia, the risk of rabies and JE often overlap. Therefore, all travelers to these regions are advised to receive both a rabies and JE vaccination, regardless if they are traveling for leisure or business (including expatriates, military personnel and their families). Despite such recommendations, a disproportionately low number of individuals seek out the rabies and/or JE vaccines prior to travel [5e9]. It has been suggested that the relatively long period needed to administer the current rabies and JE vaccinations (up to four weeks for both), may be a reason for the low vaccination rates [3,5,6,9]. For
example, in a large survey of US travelers to Asia, a significant proportion stated that they were unable to receive a rabies vaccine due to insufficient time to complete the vaccination regimen prior to departure [6]. Furthermore, a European survey of 609 travelers found that of those who had consulted a travel clinic, over 40% visited the clinic four weeks or less prior to departure, and 20% had just planned their trip in the previous two weeks [10]. This suggests that shorter immunization regimens are needed by many travelers. Indeed, to encourage optimal protection, concomitant administration of multiple vaccines would be most convenient. This study thus sought to determine the non-inferiority of immune responses to a rabies vaccine (Rabipur Novartis Vaccines) administered concomitantly with a JE vaccine (Ixiaro, Valneva), according to an accelerated (one-week) regimen, compared to the standard four-week rabies regimen. The immunogenicity against rabies following concomitant administration of the two vaccines according to the standard four-week regimen was also evaluated, in addition to the tolerability of all vaccine combinations. Short-term immunogenicity and safety up to Day 57 are presented.
2. Methods 2.1. Study design This Phase IIIb randomized, observer-blind, multi-center study was conducted at seven centers in Austria, Germany and Switzerland (NCT01662440). The study was undertaken in compliance with Good Clinical Practice and the Declaration of Helsinki (version 2008). Ethics review committees of participating centers approved the protocol and its
Accelerated rabies and JE vaccination regimen amendments, and written informed consent was obtained from every participant prior to enrollment.
2.2. Study participants Enrolled subjects (N Z 661) were volunteers, aged 18 to 65 years, who were randomized into 4 vaccine groups by a web-based randomization system. The subjects were assigned in a 3:4:4:1 ratio into one of four vaccine groups:
243 1) a standard regimen (Rabies þ JE-Standard group); 2) rabies plus JE according to an accelerated regimen (Rabies þ JE-Accelerated); 3) rabies alone according to a standard regimen (Rabies-Standard group); or 4) JE alone according to a standard regimen (JE-Standard group; data not included, to be reported in a separate manuscript). Differences in vaccination schedule between Groups 1-4 were supplemented with corresponding placebo injections. See Fig. 1 for vaccination groups and study design. Please
Figure 1 Flow chart of study design for all Groups: Rabies þ JE-Standard; Rabies þ JE-Accelerated; Rabies-Standard; and JEStandard. N numbers indicate the number of subjects included in the immunogenicity analyses (PPS) at each time point. There were 9 premature withdrawals in the Rabies þ JE-Standard group, 6 in the Rabies þ JE Rapid Group, 6 in the Rabies Standard Group, and 4 in the JE Standard Group. JE, Japanese encephalitis. *Please note that data comparing the immunogenicity of the JE vaccine (shaded in gray) with other groups are being reported in a separate manuscript.
244 note that the data presented in this manuscript are part of a larger investigation (NCT01662440). The focus of the present manuscript is on short-term immunogenicity and safety of the rabies vaccine from Day 1 (corresponding to Day 0 on the product label) to Day 57. Short-term immunogenicity and safety of the JE vaccine, as well as longterm immunogenicity and safety of both the rabies and JE vaccines will be reported separately. Eligible study participants were healthy adults of either sex aged 18e65 years. Subjects were excluded if they had: a fever (38 C) within three days of the intended vaccination; a known reaction to any vaccine component; previously received or planned to receive any investigational vaccines prior to completion of the study; received any other vaccines within two weeks prior to enrollment or planned to receive any vaccine within four weeks of receiving the study vaccines; or received/planned to receive anti-malaria drugs up to 14 days prior to vaccination through Day 43; a history of rabies immunoglobulin and/or JE immunization. In addition, study personnel, close family members, subjects who may be offered a rabies and/or JE vaccine within the year because they were planning to travel to at-risk areas, and pregnant or breast-feeding women were also excluded from participation. The duration of the study and planned participation of the subjects was 1 year.
2.3. Vaccines Two commercially available vaccines were used in this study. The purified chick embryo cell-culture rabies vaccine, Rabipur, containing inactivated rabies virus (strain: Flury-LEP-C26; Novartis Vaccines) is licensed in the EU and USA and several other countries for both pre- and postexposure prophylaxis of rabies in individuals of all ages [11]. Ixiaro (Valneva) is an inactivated aluminum adjuvanted JE vaccine (strain: SA14-14-2), which is also licensed in the EU, USA as well as in several other countries for active immunization against JE in adults and children aged two months [12]. The rabies vaccine was given as a threedose regimen (1.0 mL doses) and the JE vaccine as a twodose regimen (0.5 mL doses; see Fig. 1 for vaccine administrations). Placebo treatment consisted of physiological saline (0.9% w/v sodium chloride). Vaccines were administered intramuscularly into the deltoid region of either the right arm (rabies vaccine or placebo) or the left arm (JE vaccine or placebo) in an observer-blind fashion by designated unblinded site staff. The investigator and all other study personnel, including those interviewing the subjects for adverse events, remained blinded.
2.4. Immunogenicity assessment Blood samples were obtained at baseline (Day 1) and on Days 8, 15, 36, and 57. Sera were then stored at 18 C until analysis. Antibody responses to the rabies vaccine, measured as rabies virus neutralizing antibody (RVNA) levels, were assessed by the rapid fluorescent focus inhibition test (RFFIT), which was performed at the Kansas State University Rabies Laboratory, Kansas, US [13]. The RFFIT measures the ability of RVNAs present in a serum sample to neutralize and block rabies virus from infecting
T. Jelinek et al. baby hamster kidney (BHK-21) cells in the presence of a BHK-21 adapted challenge virus standard. Antibody levels are expressed as geometric mean concentrations (GMCs), and the antibody level considered adequate for protection against rabies is defined as the percentage of subjects with RVNA concentrations 0.5 IU/mL. Serology assays were performed in a blinded fashion for all vaccine groups and visits.
2.5. Safety assessment Following each vaccination, subjects were observed for at least 30 min to monitor for immediate adverse reactions. Solicited local and systemic adverse events (AEs) were recorded by the participants in a diary card for seven days following each vaccination. Since vaccinations were not always separated by at least seven days, solicited AEs could not always be associated with only one treatment. Therefore, when two different treatments (i.e. rabies and placebo) were consecutively administered in the same injection site less than seven days apart, the relative solicited local and systemic AEs were attributed to both treatments for the overlapping period (i.e. from Day 4 to Day 7). When the same treatment (i.e. rabies or placebo) was consecutively administered in the same injection site more than seven days apart, the relative solicited local and systemic AEs were attributed only to one group. Reports of unsolicited AEs and serious AEs (SAEs) were collected up to Day 57. Selected solicited local reactions were: injection site pain, erythema, and induration. Selected solicited systemic reactions were: arthralgia, fatigue, headache, changes in appetite, myalgia, nausea, and temperature 38 C. The investigators also assessed all AEs for severity and its relation to the study vaccines. The severity of AEs was categorized as mild, moderate, or severe. Assessments of the causal relationship of AEs to the study vaccines were classified as not related, possibly related, or probably related.
2.6. Study objectives and statistical analyses The primary objective of this study was to establish noninferiority of the immune response of the Rabies þ JEAccelerated regimen compared to the Rabies-Standard regimen. The criterion for non-inferiority was that the lower limit of the two-sided 97.5% confidence interval (CI) for the differences in percentages of subjects (Rabies þ JEAccelerated minus Rabies-Standard) with RVNA concentrations 0.5 IU/mL 7 days after last vaccination (Day 15 for the accelerated schedule and Day 36 for the conventional schedule) was greater than the predefined limit of 5%. The secondary objectives for the study were to: 1) establish non-inferiority of the Rabies þ JE-Standard regimen compared to the Rabies-Standard regimen, where the criterion for non-inferiority was that the lower limit of the two-sided 95% CI for the ratios of GMTs 28 days after the last vaccination (Day 36 for the accelerated schedule and Day 57 for the conventional schedule) was greater than 0.66; 2) establish non-inferiority of the immune response for the Rabies þ JE-Accelerated regimen compared to both the Rabies-Standard regimen as well as the Rabies þ JEStandard regimen, where the criterion for non-inferiority
Accelerated rabies and JE vaccination regimen was that the lower limit of the two-sided 95% CI for the differences in percentage of subjects with RVNA concentrations 0.5 IU/mL 28 days after last vaccination was greater than 5%; and 3) evaluate the kinetics of antibody responses for all groups receiving the rabies vaccine (percentages of subjects with RVNA concentrations 0.5 IU/mL, as well as RVNA GMCs on Days 1, 8, 15, 36 and 57). Assuming a dropout rate of approximately 9%, 220 subjects were enrolled for the Rabies þ JE-Accelerated and Rabies-Standard groups. This would provide 200 subjects per group, which would have at least 90% power to meet the primary objective. The percentages of subjects with RVNA concentrations of 0.5 IU/mL and the associated 95% Clopper-Pearson CI were calculated by group. RVNA GMCs and their associated 95% CIs by group and by time point were calculated by exponentiating the corresponding log-transformed (least squares) means, and their 95% CIs were obtained from an ANOVA model. Immunogenicity analyses were run on the perprotocol set (PPS), which included all subjects in the full analysis set who received the relevant doses of vaccines correctly, provided evaluable serum samples at the relevant time points and within the study-specified visit windows through Day 57, and who had no major protocol violations. See Fig. 1 for the number of subjects included in the immunogenicity analyses at each time point. Safety was evaluated on all subjects who had received at least one vaccination and who provided solicited and/or unsolicited safety data.
3. Results 3.1. Disposition and demographics Of the 605 subjects included in this study, all but one were exposed to at least one dose of vaccine. Less than 10% of subjects had protocol deviations that led to exclusion of data from one or more immunogenicity analysis sets. Reasons for exclusions were primarily missed blood draws or blood draws taken outside of time windows for clinical visits. Two subjects were excluded from the unsolicited safety set: one because no post-vaccination safety information was provided, and one because they did not receive a vaccination due to violation of the inclusion criteria. All three groups were comparable with respect to age, weight, height and race (Table 1). There were, however, Table 1
245 slightly more females in most groups (57%e59%), with the exception of the Rabies þ JE-Standard group (46%). This slight imbalance in sex between groups did not result in any difference in terms of an immune response.
3.2. Immunogenicity Pre-existing RVNA concentrations (0.5 IU/mL) on Day 1 were detected in approximately 1% of subjects across all groups (2, 1 and 3 individuals from the Rabies þ JE-Accelerated, Rabies þ JE-Standard and Rabies Standard groups, respectively). The results of the non-inferiority analyses for the primary and secondary objectives are shown in Table 2. As demonstrated, non-inferiority of the immune response was successfully established for the Rabies þ JE-Accelerated vaccine regimen compared to the Rabies-Standard regimen, i.e. the lower limit of the 2-sided 97.5% CI for group differences seven days after administration of the last vaccination was 2.8%, which is above the pre-specified noninferiority margin of 5% (Table 2). In addition, noninferiority of the immune response was established for the Rabies þ JE-Accelerated regimen compared to both the Rabies-Standard regimen and the Rabies þ JE-Standard regimen, i.e. the lower limit of the 2-sided 95% CI for group differences 28 days after the last vaccination was 4.2% for the Rabies þ JE-Accelerated versus Rabies þ JE-Standard regimen, and 3.8% for the Rabies þ JE-Accelerated versus the Rabies-Standard regimen, both of which are above the pre-specified non-inferiority margin of 5% (Table 2). Finally, non-inferiority of the immune response was also established for the Rabies þ JE-Standard regimen compared to the Rabies-Standard regimen, i.e. the lower limit of the two-sided 95% CI for the ratio of GMTs (Rabies þ JE-Standard: Rabies-Standard) was 0.86, which is above the prespecified non-inferiority margin of 0.66 (Table 2). Noninferiority was also established using a tighter noninferiority margin of 0.75, i.e. where the lower limit of the two-sided 95% CI for the ratio of GMCs (Rabies þ JE-Standard: Rabies-Standard) is greater than 0.75. In addition to establishing non-inferiority, the kinetics of antibody responses to the different rabies vaccination regimens were evaluated. Fig. 2A shows reverse cumulative distribution curves of RVNA titers for each group on Days 8, 15, 36, and 57. By Day 57, as many as 97% of subjects in the
Study population demographics of enrolled subjects.
Age, years (Mean SD) Male, n (%) Female, n (%) Weight, kg (Mean SD) Height, cm (Mean SD) Race, n (%) White Black/African American Asian Other
Rabies þ JE-Standard
Rabies þ JE-Accelerated
Rabies-Standard
N Z 167
N Z 217
N Z 221
37.3 13.4 91 (54) 76 (46) 75.67 16.86 174.5 9.1
36.8 12.7 89 (41) 128 (59) 75.21 17.12 172.4 8.9
35.7 12.6 96 (43) 125 (57) 73.59 14.14 172.9 9.2
166 (99) 0 1 (<1) 0
213 (98) 2 (<1) 0 2 (<1)
218 (99) 0 1 (<1) 2 (<1)
JE, Japanese encephalitis; SD, standard deviation.
246 Table 2 Non-inferiority analyses between PPS groups at pre-determined analysis time points: 1) Rabies þ JE-Accelerated versus Rabies-Standard; 2) Rabies þ JE-Accelerated versus Rabies þ JE-Standard; and 3) Rabies þ JE-Standard versus Rabies-Standard. Immunogenicity endpoint
% subjects with RVNA concentrations 0.5 IU/mL 7 days post last active vaccination (95% CI)
% subjects with RVNA concentrations 0.5 IU/mL 28 days post last active vaccination (95% CI)
% subjects with RVNA concentrations 0.5 IU/mL 28 days post last active vaccination (95% CI)
RVNA GMCs 28 days post last active vaccination
Vaccine group
Non-inferiority analyses
Rabies D JE Accelerated N [ 209
Rabies Standard N [ 207
Vaccine group difference Rabies D JEAccelerated vs. Rabies-Standardb
n Z 208 100 (97e100)
n Z 206 99 (97e100)
Difference (97.5% CI)
Rabies D JE Accelerated N [ 206
Rabies D JE Standard N [ 157
Vaccine group difference Rabies D JEAccelerated vs. Rabies D JE-Standardc
n Z 203 99 (96e100)
n Z 157 100 (98e100)
Difference (95% CI)
Rabies D JE Accelerated N [ 206
Rabies Standard N [ 204
Vaccine group difference Rabies D JEAccelerated vs. Rabies-Standardc
n Z 203 99 (96e100)
n Z 203 99 (97e100)
Difference (95% CI)
Rabies D JE Standard N [ 157
Rabies Standard N [ 204
Ratio of GMTs Rabies D JE-Standard: Rabies-Standardd
11 (9e12)
9.9 (8.57e11)
Ratio of GMTs (95% CI)
0 (L2.8ae2.8)
1 (L4.2e1)
1 (L3.8e1.4)
1.07 (0.86e1.32)
CI, confidence interval; GMC, geometric mean concentration; RVNA, rabies virus neutralizing antibody. N Z number of subjects with evaluable samples at the relevant time points (Day 7 and Day 28). n Z number above the threshold. a Bolded numbers indicate that non-inferiority criteria were met. Non-inferiority was defined as follows. b The lower limit of the two-sided 97.5% confidence interval (CI) for the differences in % subjects with RVNA concentrations 0.5 IU/mL 7 days after last vaccination was >5%. c The lower limit of the two-sided 95% CI for the differences in % subjects with RVNA concentrations 0.5 IU/mL 28 days after last vaccination was >5%. d The lower limit of the two-sided 95% CI for the ratios of the GMTs 28 days after last vaccination was >0.66.
T. Jelinek et al.
Accelerated rabies and JE vaccination regimen
247
Figure 2 (A) Reverse cumulative distribution curves showing RVNA GMCs on Days 8, 15, 36 and 57; the RVNA threshold of 0.5 IU/ mL is indicated in each graph with a dashed line; (B) Percentage of subjects with RVNA concentrations 0.5 IU/mL. Arrows indicate days on which different vaccinations were administered to the different groups (specific vaccines administered are indicated in parentheses: R, rabies vaccination; JE: Japanese Encephalitis vaccination).
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Rabies þ JE-Accelerated group were still above the antibody level indicative of adequate immune response after immunization (RVNA 0.5 IU/mL), compared to 99% and 100% of subjects in the Rabies-Standard and Rabies þ JEStandard groups, respectively (Fig. 2B). GMCs (Fig. 2A) and the percentages of subjects with RVNA concentrations 0.5 IU/mL (Fig. 2B) were similar in both the Rabies þ JEStandard and the Rabies-Standard groups at all time points.
3.3. Safety The percentage of subjects experiencing at least one solicited AE after any vaccination was similar across all groups, and ranged from 82% (Rabies-Standard group) to 85% (Rabies þ JE-Accelerated; Table 3). Solicited AEs were typically mild to moderate; severe AEs were reported in less than 4% of subjects. Unsolicited AEs were reported by 42% of subjects in the Rabies þ JE-Standard group and 50% of subjects in the Rabies þ JE-Accelerated and RabiesStandard groups (Table 3). The most frequent unsolicited AEs were nasopharyngitis (from 13% to 15%) and headache (occurring more than 7 days after vaccination; 7%e10%). Possibly or probably related AEs were reported by 18%e23% of subjects across groups, with nasopharyngitis being the most frequently related AE reported (5% in the RabiesStandard group, and 4% in the Rabies þ JE-Accelerated group). Seven subjects reported SAEs. For two subjects (both in the Rabies-Standard group), the SAEs were judged as possibly or probably related to the vaccine: one subject had atrial fibrillation on study Day 9, and the other tachycardia and syncope on study Day 10. Both resolved by Day 57. No deaths were reported.
4. Discussion Non-inferiority of antibody responses was demonstrated for the concomitant accelerated (one-week) Rabies þ JE vaccination regimen compared to both the standard rabies (four-week) regimen and the standard Rabies þ JE regimen (four-week). Immune responses to the rabies vaccine were evaluated by measuring RVNA concentrations which, based on previous immunogenicity data, are thought to be the
Table 3
adequate immunogenicity endpoint following rabies immunization, and there is consensus that levels at or above 0.5 IU/mL are protective against rabies [14,15]. In this study, the RFFIT assay, which is the “gold standard” for measuring RVNA concentrations [16], and which is recommended by the WHO [15], was performed at a highly experienced commercial laboratory [13]. As expected, there was a quicker decline in rabies GMCs between Days 15 and 57 in the accelerated regimen group compared to the two standard regimen groups. This is because in the accelerated regimen, the final vaccination was administered on Day 8, whereas in the standard regimens it was administered on Day 29. However, despite differences in short-term antibody kinetics, at Day 57 the vast majority of all subjects (97e100%) had RVNA levels of 0.5 IU/mL. In addition, vaccine tolerability and safety profiles were similar across all groups. The results from the present study also provide support for the use of the standard concomitant Rabies þ JE vaccination regimen; namely, antibody responses to the standard concomitant (Rabies þ JE) regimen were noninferior to those of the standard rabies regimen. GMCs and the percentage of subjects with RVNA concentrations 0.5 IU/mL were similar in both the Rabies þ JE-Standard and the Rabies-Standard groups at all time points from Days 1e57. Moreover, by Day 57, 99% and 100% of subjects in the Rabies-Standard and Rabies þ JE-Standard groups, respectively, were above the antibody level indicative of protection (RVNA 0.5 IU/mL). These finding are consistent with a previous report that concomitant administration of a rabies (Rabipur) and JE (inactivated, mouse-brain derived; Biken) vaccine in toddlers induced adequate and long lasting antibody responses [17]. Vaccine tolerability and safety profiles in the present study were similar for both standard vaccination groups. The ‘0-3-7’ rabies regimen (equivalent to vaccinations on Days 1, 4 and 8 as described in this study) was chosen on the basis that previous studies have demonstrated good immune responses using this regimen [18e20]. Khawplod et al., for example, demonstrated that subjects receiving a shortened pre-exposure rabies vaccination regimen (intramuscular doses on Days 0, 3, and 7) had detectable
Percentage of subjects reporting adverse events (solicited and unsolicited safety sets). Rabies þ JE-Standard N Z 166
Solicted AEs reported from Day 1 to Day 7 (%) Any solicited AEs 83 Local 75 Systemic 60 Other 17 Unsolicited AEs reported from Day 1 to Day 57 (%) Any unsolicited AEs 42 Possibly or probably related AEs 18 AEs leading to premature withdrawal 1 Any SAEs 1 Possibly or probably related SAEs 0
Rabies þ JE-Accelerated N Z 217
Rabies-Standard N Z 220
85 74 66 17
82 73 62 18
50 23 0 1 0
50 22 0 1 1
AE, adverse event; JE, Japanese encephalitis; SAE, serious adverse event. Number of SAEs reported by group: Rabies þ JE Standard: 2 subsects; Rabies þ JE Accelerated: 3 subjects; Rabies standard: 2 subjects.
Accelerated rabies and JE vaccination regimen neutralizing antibody levels one year later [18]. Moreover, Thraenhart and colleagues (among others) have long suggested that the first three vaccinations on Days 0, 3, and 7 for post-exposure prophylaxis are the most important in terms of inducing rapid immunogenicity [20,21]. Likewise, a one-week intradermal regimen for post-exposure rabies prophylaxis (4 doses given on Days 0, 3 and 7) has been shown to be immunogenic with an acceptable safety profile [19]. While the findings in this study are positive, there are a number of limitations to consider. Firstly, since experimental virus challenge is not possible in humans, immunogenicity of the rabies vaccine can only be assessed through surrogate markers. Clearly, surrogate markers are not direct correlates of protection. However, an RVNA level of 0.5 IU/ml has been established as a globally recognized indicator of an adequate response to vaccination against rabies in humans [15,16]. Secondly, the absence of a separate Rabies-Accelerated vaccination group could be considered a potential limitation to this study. The inclusion of such a group might have provided direct evidence to eliminate the possibility that the JE vaccine was serving to boost the immune response to the rabies vaccine. However, this is unlikely since in the present study there was no evidence of this in the standard rabies vaccination group, i.e. the immune responses were very similar in both the Rabies þ JE-Standard and Rabies-Standard groups. Finally, the finding that the accelerated concomitant Rabies þ JE regimen is as effective as the standard rabies regimen only pertains to the short-term period. Long-term data collected at twelve months will be used to determine whether the Rabies þ JE-Accelerated regimen elicits comparable protection to the standard regimen over a longer period. In conclusion, the data from this study demonstrate that a rabies vaccine administered concomitantly with a JE vaccine according to an accelerated (one-week) regimen has a similar short-term immune response and an equally acceptable safety profile to that obtained with either a standard rabies (four-week) or standard combination Rabies þ JE (four-week) regimen. The use of the concomitant regimen is expected to be particularly useful for travelers requiring rabies and JE vaccinations less than one month before travel. Importantly, the immune response to the concomitant Rabies þ JE vaccination regimen (accelerated or standard) was non-inferior to the standard rabies regimen alone. There were also no safety concerns with any vaccination regimen. Ultimately, the possibility of a concomitant (accelerated or standard) Rabies þ JE vaccination regimen offers a convenient and time-saving option particularly suited to short-notice travelers, and should encourage higher numbers to seek out prophylactic protection.
Author contributions TJ, JPC, SD, CH, MP-K, MA, ECR participated in the conduct of the study, data acquisition and interpretation, and contributed to the development of the manuscript. MC participated in the conception, design, statistical analysis, interpretation of analyzed data, and development of the manuscript. DG, DB and ML participated in the conception,
249 design and implementation of the study, interpretation of analyzed data, and development of the manuscript.
Conflicts of interests ML, and MC were full time employees of Novartis group companies at the time of the study, and are now employees of GSK group companies. DB and DG were full-time employees of Novartis Vaccines at the time of the study. TJ was an investigator on the study and received compensation from Novartis Vaccines. MPK accepted fees for speaking and serving on advisory boards and received funding to attend conferences from Baxter, GlaxoSmithKline, Valneva (former Intercell), Novartis and Pfizer. JPC received financial support for conducting this study and has accepted honoraries from Novartis as well as from Valneva/ Intercell for presentations and consulting. CH has received unrestricted educational grants from Novartis, GlaxoSmithKline and Crucell. ECR received financial support for conducting this study and has accepted honoraria from Novartis as well as from Infectopharm, Astellas, Pfizer, Bayer and CureVac for presentations, consulting and travel expenses. SD and MA have no conflicts of interest to disclose.
Funding This study was sponsored by Novartis Vaccines and Diagnostics GmbH.
Acknowledgments The authors would like to thank: All the study participants and Investigators; Kelly Lindert and Ahmed Abdul Mateen for their contribution to the study design; Khaleel Ahmed and Michele Pellegrini for their contribution to study implementation and interpretation of results; and Yvonna Fisher-Jeffes (GlaxoSmithKline LLC, US) and Amanda Prowse (CHC-Europe) for their editorial assistance in the preparation of the manuscript.
References [1] Malerczyk C, Detora L, Gniel D. Imported human rabies cases in Europe, the United States, and Japan, 1990 to 2010. J Travel Med 2011;18:402e7. [2] World Health Organization. International travel and health. Rabies. Available from: http://www.who.int/ith/vaccines/ rabies/en/ [accessed March 2014]. [3] Gautret P, Parola P. Rabies vaccination for international travelers. Vaccine 2012;30:126e33. [4] World Health Organization. International travel and health. Chapter 6. Vaccine-preventable diseases and vaccines 2013 update. Available from: http://www.who.int/ith/chapters/ ith2012en_chap6.pdf?uaZ1 [acessed March 2014]. [5] Altmann M, Parola P, Delmont J, Brouqui P, Gautret P. Knowledge, attitudes, and practices of French travelers from Marseille regarding rabies risk and prevention. J Travel Med 2009;16:107e11. [6] Dolan SB, Jentes ES, Sotir MJ, Han P, Blanton JD, Rao SR, et al. Pre-exposure rabies vaccination among US international
250
[7]
[8]
[9]
[10]
[11]
[12]
[13] [14]
T. Jelinek et al. travelers: findings from the Global TravEpiNet Consortium. Vector Borne Zoonotic Dis 2014;14:160e7. Duffy MR, Reed C, Edelson PJ, Blumensaadt S, Crocker K, Griggs A, et al. A survey of US travelers to Asia to assess compliance with recommendations for the use of Japanese encephalitis vaccine. J Travel Med 2013;20:165e70. Gautret P, Tantawichien T, Vu Hai V, Piyaphanee W. Determinants of pre-exposure rabies vaccination among foreign backpackers in Bangkok, Thailand. Vaccine 2011;29:3931e4. Piyaphanee W, Shantavasinkul P, Phumratanaprapin W, Udomchaisakul P, Wichianprasat P, Benjavongkulchai M, et al. Rabies exposure risk among foreign backpackers in Southeast Asia. Am J Trop Med Hyg 2010;82:1168e71. Van Herck K, Zuckerman J, Castelli F, Van Damme P, Walker E, Steffen R, et al. Travelers’ knowledge, attitudes, and practices on prevention of infectious diseases: results from a pilot study. J Travel Med 2003;10:75e8. Rabipur. Summary of product characteristics. Available from: http://www.eda.mohp.gov.eg/Download/Docs/Files/36_SPC. pdf. [accessed March 2014]. IXIARO. Summary of product characteristics. Available from: http://www.ema.europa.eu/docs/en_GB/document_library/ EPAR_-_Product_Information/human/000963/WC500037287. pdf. [accessed March 2014]. Kansas State University Rabies Laboratory. http://www.vet.kstate.edu/depts/dmp/service/rabies/. Plotkin SA. Correlates of protection induced by vaccination. Clin Vaccine Immunol 2010;17:1055e65.
[15] World Health Organisation. Rabies vaccines. WHO position paper. Wkly Epidemiol Rec (WER) 2010;85:309e20. [16] Moore SM, Hanlon CA. Rabies-specific antibodies: measuring surrogates of protection against a fatal disease. PLoS Negl Trop Dis 2010;4:e595. [17] Pengsaa K, Limkittikul K, Sabchareon A, Ariyasriwatana C, Chanthavanich P, Attanath P, et al. A three-year clinical study on immunogenicity, safety, and booster response of purified chick embryo cell rabies vaccine administered intramuscularly or intradermally to 12- to 18-month-old Thai children, concomitantly with Japanese encephalitis vaccine. Pediatr Infect Dis J 2009;28:335e7. [18] Khawplod P, Wilde H, Benjavongkulchai M, Sriaroon C, Chomchey P. Immunogenicity study of abbreviated rabies preexposure vaccination schedules. J Travel Med 2007;14: 173e6. [19] Shantavasinkul P, Tantawichien T, Wilde H, Sawangvaree A, Kumchat A, Ruksaket N, et al. Postexposure rabies prophylaxis completed in 1 week: preliminary study. Clin Infect Dis 2010; 50:56e60. [20] Thraenhart O, Marcus I, Scheiermann N. 3e1 scheme, a regimen of only two clinic visits with optimal antibody and interferon-induction progress in rabies control. Kent, England: Wells Medical; 1989. p. 536e47. [21] Wilde H, Shantavasinkul P, Hemachudha T, Tepsumethanon V, Lumlertacha B, Wacharapluesadee S, et al. New knowledge and controversies in rabies. J Infect Dis Antimicrob Agents 2009;26:63e74.
Available online at www.sciencedirect.com
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Evaluation of rabies immunogenicity and tolerability following a purified chick embryo cell rabies vaccine administered concomitantly with a Japanese encephalitis vaccine* Tomas Jelinek a, Jakob P. Cramer b, Sebastian Dieckmann c, Christoph Hatz d, Maria Paulke-Korinek e, Martin Alberer f, Emil C. Reisinger g, Marco Costantini h, Dieter Gniel i, Dietrich Bosse i, Maria Lattanzi h,* a
Berlin Center for Travel and Tropical Medicine, Berlin, Germany Bernhard Nocht Institute for Tropical Medicine, Department of Clinical Research/University Medical Center Hamburg-Eppendorf, Department of Internal Medicine, Section Tropical Medicine, Hamburg, Germany c Institute of Tropical Medicine and International Health, Charite´-Universitaetsmedizin Berlin, Germany d Institute of Social and Preventive Medicine, University of Zu¨rich, Switzerland e Institute of Specific Prophylaxis and Tropical Medicine, Medical University Vienna, Austria f Department of Infectious Diseases and Tropical Medicine, University of Munich, Munich, Germany g Department of Tropical Medicine and Infectious Diseases, University of Rostock Medical School, Rostock, Germany h Novartis Vaccines and Diagnostics Srl e a GSK company, Siena, Italy i Novartis Vaccines and Diagnostics Srl e a GSK company, Marburg, Germany b
Received 3 November 2014; received in revised form 30 April 2015; accepted 3 May 2015
Available online 18 May 2015
Abbreviations: GMC, geometric mean concentrations; JE, Japanese encephalitis; RVNA, rabies virus neutralizing antibody. * This study has been presented at the Northern European Conference on Travel Medicine (NECTM), June 5e8, 2014, Bergen, Norway. * Corresponding author. Novartis Vaccines and Diagnostics Srl e a GSK company, Via Fiorentina, 1, 53100 Siena, Italy. Tel.: þ39 0577245273. E-mail address: [email protected] (M. Lattanzi). http://dx.doi.org/10.1016/j.tmaid.2015.05.008 1477-8939/ª 2015 Elsevier Ltd. All rights reserved.
242
KEYWORDS Rabies; Japanese encephalitis; Vaccination
T. Jelinek et al.
Summary Background: For individuals traveling at short notice to rabies and Japanese encephalitis (JE) endemic countries, concomitant administration of travel vaccines within a short period is often required. Methods: The aim of this study was to determine whether an accelerated (one-week: Days 1 e8) pre-exposure rabies (Rabipur , Novartis Vaccines) vaccination regimen administered concomitantly with a Japanese encephalitis (JE) vaccination (Ixiaro, Valneva) regimen, is non-inferior to the standard (four-week: Days 1, 8, 29) rabies regimen administered alone or concomitantly with the JE vaccine. Healthy adults (18 to 65 years) were randomized into Rabies þ JE-Standard, Rabies þ JE-Accelerated, Rabies-Standard and JE-Standard groups. Relative immunogenicity for rabies in each regimen was assessed using the rapid fluorescent focus inhibition test. Safety was evaluated up to and including Day 57. Results: Non-inferior immunogenicity for rabies was established between the Rabies þ JEAccelerated group compared to both the Rabies-Standard and Rabies þ JE-Standard groups; as well as between the Rabies þ JE-Standard regimen and the Rabies-Standard regimen. By Day 57, adequate neutralizing levels were achieved by 97e100% of subjects across all groups. Adverse events (AEs) were comparable for all groups. Conclusions: An accelerated pre-exposure rabies and JE vaccination regimen is non-inferior to the standard four-week rabies regimen and may thus provide a more convenient regimen for individuals traveling to endemic countries at short notice. NCT01662440. ª 2015 Elsevier Ltd. All rights reserved.
1. Introduction Rabies and Japanese encephalitis (JE) are serious diseases that are of concern to individuals traveling to countries where these conditions are prevalent. Prophylactic vaccinations against these diseases are thus recommended, particularly for prolonged trips and/or if access to medical care will be limited [1,2]. Rabies especially is a problem across large parts of Africa, India and Asia, where the incidence of injuries to travelers caused by potentially rabid animals is estimated to be approximately 0.4% per month of stay [3]. Pre-exposure rabies vaccination helps provide effective protection by inducing immunological memory. The regimen consists of three full intramuscular doses of a cell-culture based vaccine administered over a three to four week period [4]. The World Health Organization (WHO) International Travel and Health [4] recommends that travelers who are planning extensive outdoor exposure in endemic countries (e.g. camping, hiking etc.), particularly during the rainy season receive adequate immunization against JE prior to travel. Primary JE immunization consists of two intramuscular doses with an inactivated Vero cell-derived JE vaccine, administered four weeks apart [4]. In many countries in Asia, the risk of rabies and JE often overlap. Therefore, all travelers to these regions are advised to receive both a rabies and JE vaccination, regardless if they are traveling for leisure or business (including expatriates, military personnel and their families). Despite such recommendations, a disproportionately low number of individuals seek out the rabies and/or JE vaccines prior to travel [5e9]. It has been suggested that the relatively long period needed to administer the current rabies and JE vaccinations (up to four weeks for both), may be a reason for the low vaccination rates [3,5,6,9]. For
example, in a large survey of US travelers to Asia, a significant proportion stated that they were unable to receive a rabies vaccine due to insufficient time to complete the vaccination regimen prior to departure [6]. Furthermore, a European survey of 609 travelers found that of those who had consulted a travel clinic, over 40% visited the clinic four weeks or less prior to departure, and 20% had just planned their trip in the previous two weeks [10]. This suggests that shorter immunization regimens are needed by many travelers. Indeed, to encourage optimal protection, concomitant administration of multiple vaccines would be most convenient. This study thus sought to determine the non-inferiority of immune responses to a rabies vaccine (Rabipur Novartis Vaccines) administered concomitantly with a JE vaccine (Ixiaro, Valneva), according to an accelerated (one-week) regimen, compared to the standard four-week rabies regimen. The immunogenicity against rabies following concomitant administration of the two vaccines according to the standard four-week regimen was also evaluated, in addition to the tolerability of all vaccine combinations. Short-term immunogenicity and safety up to Day 57 are presented.
2. Methods 2.1. Study design This Phase IIIb randomized, observer-blind, multi-center study was conducted at seven centers in Austria, Germany and Switzerland (NCT01662440). The study was undertaken in compliance with Good Clinical Practice and the Declaration of Helsinki (version 2008). Ethics review committees of participating centers approved the protocol and its
Accelerated rabies and JE vaccination regimen amendments, and written informed consent was obtained from every participant prior to enrollment.
2.2. Study participants Enrolled subjects (N Z 661) were volunteers, aged 18 to 65 years, who were randomized into 4 vaccine groups by a web-based randomization system. The subjects were assigned in a 3:4:4:1 ratio into one of four vaccine groups:
243 1) a standard regimen (Rabies þ JE-Standard group); 2) rabies plus JE according to an accelerated regimen (Rabies þ JE-Accelerated); 3) rabies alone according to a standard regimen (Rabies-Standard group); or 4) JE alone according to a standard regimen (JE-Standard group; data not included, to be reported in a separate manuscript). Differences in vaccination schedule between Groups 1-4 were supplemented with corresponding placebo injections. See Fig. 1 for vaccination groups and study design. Please
Figure 1 Flow chart of study design for all Groups: Rabies þ JE-Standard; Rabies þ JE-Accelerated; Rabies-Standard; and JEStandard. N numbers indicate the number of subjects included in the immunogenicity analyses (PPS) at each time point. There were 9 premature withdrawals in the Rabies þ JE-Standard group, 6 in the Rabies þ JE Rapid Group, 6 in the Rabies Standard Group, and 4 in the JE Standard Group. JE, Japanese encephalitis. *Please note that data comparing the immunogenicity of the JE vaccine (shaded in gray) with other groups are being reported in a separate manuscript.
244 note that the data presented in this manuscript are part of a larger investigation (NCT01662440). The focus of the present manuscript is on short-term immunogenicity and safety of the rabies vaccine from Day 1 (corresponding to Day 0 on the product label) to Day 57. Short-term immunogenicity and safety of the JE vaccine, as well as longterm immunogenicity and safety of both the rabies and JE vaccines will be reported separately. Eligible study participants were healthy adults of either sex aged 18e65 years. Subjects were excluded if they had: a fever (38 C) within three days of the intended vaccination; a known reaction to any vaccine component; previously received or planned to receive any investigational vaccines prior to completion of the study; received any other vaccines within two weeks prior to enrollment or planned to receive any vaccine within four weeks of receiving the study vaccines; or received/planned to receive anti-malaria drugs up to 14 days prior to vaccination through Day 43; a history of rabies immunoglobulin and/or JE immunization. In addition, study personnel, close family members, subjects who may be offered a rabies and/or JE vaccine within the year because they were planning to travel to at-risk areas, and pregnant or breast-feeding women were also excluded from participation. The duration of the study and planned participation of the subjects was 1 year.
2.3. Vaccines Two commercially available vaccines were used in this study. The purified chick embryo cell-culture rabies vaccine, Rabipur, containing inactivated rabies virus (strain: Flury-LEP-C26; Novartis Vaccines) is licensed in the EU and USA and several other countries for both pre- and postexposure prophylaxis of rabies in individuals of all ages [11]. Ixiaro (Valneva) is an inactivated aluminum adjuvanted JE vaccine (strain: SA14-14-2), which is also licensed in the EU, USA as well as in several other countries for active immunization against JE in adults and children aged two months [12]. The rabies vaccine was given as a threedose regimen (1.0 mL doses) and the JE vaccine as a twodose regimen (0.5 mL doses; see Fig. 1 for vaccine administrations). Placebo treatment consisted of physiological saline (0.9% w/v sodium chloride). Vaccines were administered intramuscularly into the deltoid region of either the right arm (rabies vaccine or placebo) or the left arm (JE vaccine or placebo) in an observer-blind fashion by designated unblinded site staff. The investigator and all other study personnel, including those interviewing the subjects for adverse events, remained blinded.
2.4. Immunogenicity assessment Blood samples were obtained at baseline (Day 1) and on Days 8, 15, 36, and 57. Sera were then stored at 18 C until analysis. Antibody responses to the rabies vaccine, measured as rabies virus neutralizing antibody (RVNA) levels, were assessed by the rapid fluorescent focus inhibition test (RFFIT), which was performed at the Kansas State University Rabies Laboratory, Kansas, US [13]. The RFFIT measures the ability of RVNAs present in a serum sample to neutralize and block rabies virus from infecting
T. Jelinek et al. baby hamster kidney (BHK-21) cells in the presence of a BHK-21 adapted challenge virus standard. Antibody levels are expressed as geometric mean concentrations (GMCs), and the antibody level considered adequate for protection against rabies is defined as the percentage of subjects with RVNA concentrations 0.5 IU/mL. Serology assays were performed in a blinded fashion for all vaccine groups and visits.
2.5. Safety assessment Following each vaccination, subjects were observed for at least 30 min to monitor for immediate adverse reactions. Solicited local and systemic adverse events (AEs) were recorded by the participants in a diary card for seven days following each vaccination. Since vaccinations were not always separated by at least seven days, solicited AEs could not always be associated with only one treatment. Therefore, when two different treatments (i.e. rabies and placebo) were consecutively administered in the same injection site less than seven days apart, the relative solicited local and systemic AEs were attributed to both treatments for the overlapping period (i.e. from Day 4 to Day 7). When the same treatment (i.e. rabies or placebo) was consecutively administered in the same injection site more than seven days apart, the relative solicited local and systemic AEs were attributed only to one group. Reports of unsolicited AEs and serious AEs (SAEs) were collected up to Day 57. Selected solicited local reactions were: injection site pain, erythema, and induration. Selected solicited systemic reactions were: arthralgia, fatigue, headache, changes in appetite, myalgia, nausea, and temperature 38 C. The investigators also assessed all AEs for severity and its relation to the study vaccines. The severity of AEs was categorized as mild, moderate, or severe. Assessments of the causal relationship of AEs to the study vaccines were classified as not related, possibly related, or probably related.
2.6. Study objectives and statistical analyses The primary objective of this study was to establish noninferiority of the immune response of the Rabies þ JEAccelerated regimen compared to the Rabies-Standard regimen. The criterion for non-inferiority was that the lower limit of the two-sided 97.5% confidence interval (CI) for the differences in percentages of subjects (Rabies þ JEAccelerated minus Rabies-Standard) with RVNA concentrations 0.5 IU/mL 7 days after last vaccination (Day 15 for the accelerated schedule and Day 36 for the conventional schedule) was greater than the predefined limit of 5%. The secondary objectives for the study were to: 1) establish non-inferiority of the Rabies þ JE-Standard regimen compared to the Rabies-Standard regimen, where the criterion for non-inferiority was that the lower limit of the two-sided 95% CI for the ratios of GMTs 28 days after the last vaccination (Day 36 for the accelerated schedule and Day 57 for the conventional schedule) was greater than 0.66; 2) establish non-inferiority of the immune response for the Rabies þ JE-Accelerated regimen compared to both the Rabies-Standard regimen as well as the Rabies þ JEStandard regimen, where the criterion for non-inferiority
Accelerated rabies and JE vaccination regimen was that the lower limit of the two-sided 95% CI for the differences in percentage of subjects with RVNA concentrations 0.5 IU/mL 28 days after last vaccination was greater than 5%; and 3) evaluate the kinetics of antibody responses for all groups receiving the rabies vaccine (percentages of subjects with RVNA concentrations 0.5 IU/mL, as well as RVNA GMCs on Days 1, 8, 15, 36 and 57). Assuming a dropout rate of approximately 9%, 220 subjects were enrolled for the Rabies þ JE-Accelerated and Rabies-Standard groups. This would provide 200 subjects per group, which would have at least 90% power to meet the primary objective. The percentages of subjects with RVNA concentrations of 0.5 IU/mL and the associated 95% Clopper-Pearson CI were calculated by group. RVNA GMCs and their associated 95% CIs by group and by time point were calculated by exponentiating the corresponding log-transformed (least squares) means, and their 95% CIs were obtained from an ANOVA model. Immunogenicity analyses were run on the perprotocol set (PPS), which included all subjects in the full analysis set who received the relevant doses of vaccines correctly, provided evaluable serum samples at the relevant time points and within the study-specified visit windows through Day 57, and who had no major protocol violations. See Fig. 1 for the number of subjects included in the immunogenicity analyses at each time point. Safety was evaluated on all subjects who had received at least one vaccination and who provided solicited and/or unsolicited safety data.
3. Results 3.1. Disposition and demographics Of the 605 subjects included in this study, all but one were exposed to at least one dose of vaccine. Less than 10% of subjects had protocol deviations that led to exclusion of data from one or more immunogenicity analysis sets. Reasons for exclusions were primarily missed blood draws or blood draws taken outside of time windows for clinical visits. Two subjects were excluded from the unsolicited safety set: one because no post-vaccination safety information was provided, and one because they did not receive a vaccination due to violation of the inclusion criteria. All three groups were comparable with respect to age, weight, height and race (Table 1). There were, however, Table 1
245 slightly more females in most groups (57%e59%), with the exception of the Rabies þ JE-Standard group (46%). This slight imbalance in sex between groups did not result in any difference in terms of an immune response.
3.2. Immunogenicity Pre-existing RVNA concentrations (0.5 IU/mL) on Day 1 were detected in approximately 1% of subjects across all groups (2, 1 and 3 individuals from the Rabies þ JE-Accelerated, Rabies þ JE-Standard and Rabies Standard groups, respectively). The results of the non-inferiority analyses for the primary and secondary objectives are shown in Table 2. As demonstrated, non-inferiority of the immune response was successfully established for the Rabies þ JE-Accelerated vaccine regimen compared to the Rabies-Standard regimen, i.e. the lower limit of the 2-sided 97.5% CI for group differences seven days after administration of the last vaccination was 2.8%, which is above the pre-specified noninferiority margin of 5% (Table 2). In addition, noninferiority of the immune response was established for the Rabies þ JE-Accelerated regimen compared to both the Rabies-Standard regimen and the Rabies þ JE-Standard regimen, i.e. the lower limit of the 2-sided 95% CI for group differences 28 days after the last vaccination was 4.2% for the Rabies þ JE-Accelerated versus Rabies þ JE-Standard regimen, and 3.8% for the Rabies þ JE-Accelerated versus the Rabies-Standard regimen, both of which are above the pre-specified non-inferiority margin of 5% (Table 2). Finally, non-inferiority of the immune response was also established for the Rabies þ JE-Standard regimen compared to the Rabies-Standard regimen, i.e. the lower limit of the two-sided 95% CI for the ratio of GMTs (Rabies þ JE-Standard: Rabies-Standard) was 0.86, which is above the prespecified non-inferiority margin of 0.66 (Table 2). Noninferiority was also established using a tighter noninferiority margin of 0.75, i.e. where the lower limit of the two-sided 95% CI for the ratio of GMCs (Rabies þ JE-Standard: Rabies-Standard) is greater than 0.75. In addition to establishing non-inferiority, the kinetics of antibody responses to the different rabies vaccination regimens were evaluated. Fig. 2A shows reverse cumulative distribution curves of RVNA titers for each group on Days 8, 15, 36, and 57. By Day 57, as many as 97% of subjects in the
Study population demographics of enrolled subjects.
Age, years (Mean SD) Male, n (%) Female, n (%) Weight, kg (Mean SD) Height, cm (Mean SD) Race, n (%) White Black/African American Asian Other
Rabies þ JE-Standard
Rabies þ JE-Accelerated
Rabies-Standard
N Z 167
N Z 217
N Z 221
37.3 13.4 91 (54) 76 (46) 75.67 16.86 174.5 9.1
36.8 12.7 89 (41) 128 (59) 75.21 17.12 172.4 8.9
35.7 12.6 96 (43) 125 (57) 73.59 14.14 172.9 9.2
166 (99) 0 1 (<1) 0
213 (98) 2 (<1) 0 2 (<1)
218 (99) 0 1 (<1) 2 (<1)
JE, Japanese encephalitis; SD, standard deviation.
246 Table 2 Non-inferiority analyses between PPS groups at pre-determined analysis time points: 1) Rabies þ JE-Accelerated versus Rabies-Standard; 2) Rabies þ JE-Accelerated versus Rabies þ JE-Standard; and 3) Rabies þ JE-Standard versus Rabies-Standard. Immunogenicity endpoint
% subjects with RVNA concentrations 0.5 IU/mL 7 days post last active vaccination (95% CI)
% subjects with RVNA concentrations 0.5 IU/mL 28 days post last active vaccination (95% CI)
% subjects with RVNA concentrations 0.5 IU/mL 28 days post last active vaccination (95% CI)
RVNA GMCs 28 days post last active vaccination
Vaccine group
Non-inferiority analyses
Rabies D JE Accelerated N [ 209
Rabies Standard N [ 207
Vaccine group difference Rabies D JEAccelerated vs. Rabies-Standardb
n Z 208 100 (97e100)
n Z 206 99 (97e100)
Difference (97.5% CI)
Rabies D JE Accelerated N [ 206
Rabies D JE Standard N [ 157
Vaccine group difference Rabies D JEAccelerated vs. Rabies D JE-Standardc
n Z 203 99 (96e100)
n Z 157 100 (98e100)
Difference (95% CI)
Rabies D JE Accelerated N [ 206
Rabies Standard N [ 204
Vaccine group difference Rabies D JEAccelerated vs. Rabies-Standardc
n Z 203 99 (96e100)
n Z 203 99 (97e100)
Difference (95% CI)
Rabies D JE Standard N [ 157
Rabies Standard N [ 204
Ratio of GMTs Rabies D JE-Standard: Rabies-Standardd
11 (9e12)
9.9 (8.57e11)
Ratio of GMTs (95% CI)
0 (L2.8ae2.8)
1 (L4.2e1)
1 (L3.8e1.4)
1.07 (0.86e1.32)
CI, confidence interval; GMC, geometric mean concentration; RVNA, rabies virus neutralizing antibody. N Z number of subjects with evaluable samples at the relevant time points (Day 7 and Day 28). n Z number above the threshold. a Bolded numbers indicate that non-inferiority criteria were met. Non-inferiority was defined as follows. b The lower limit of the two-sided 97.5% confidence interval (CI) for the differences in % subjects with RVNA concentrations 0.5 IU/mL 7 days after last vaccination was >5%. c The lower limit of the two-sided 95% CI for the differences in % subjects with RVNA concentrations 0.5 IU/mL 28 days after last vaccination was >5%. d The lower limit of the two-sided 95% CI for the ratios of the GMTs 28 days after last vaccination was >0.66.
T. Jelinek et al.
Accelerated rabies and JE vaccination regimen
247
Figure 2 (A) Reverse cumulative distribution curves showing RVNA GMCs on Days 8, 15, 36 and 57; the RVNA threshold of 0.5 IU/ mL is indicated in each graph with a dashed line; (B) Percentage of subjects with RVNA concentrations 0.5 IU/mL. Arrows indicate days on which different vaccinations were administered to the different groups (specific vaccines administered are indicated in parentheses: R, rabies vaccination; JE: Japanese Encephalitis vaccination).
248
T. Jelinek et al.
Rabies þ JE-Accelerated group were still above the antibody level indicative of adequate immune response after immunization (RVNA 0.5 IU/mL), compared to 99% and 100% of subjects in the Rabies-Standard and Rabies þ JEStandard groups, respectively (Fig. 2B). GMCs (Fig. 2A) and the percentages of subjects with RVNA concentrations 0.5 IU/mL (Fig. 2B) were similar in both the Rabies þ JEStandard and the Rabies-Standard groups at all time points.
3.3. Safety The percentage of subjects experiencing at least one solicited AE after any vaccination was similar across all groups, and ranged from 82% (Rabies-Standard group) to 85% (Rabies þ JE-Accelerated; Table 3). Solicited AEs were typically mild to moderate; severe AEs were reported in less than 4% of subjects. Unsolicited AEs were reported by 42% of subjects in the Rabies þ JE-Standard group and 50% of subjects in the Rabies þ JE-Accelerated and RabiesStandard groups (Table 3). The most frequent unsolicited AEs were nasopharyngitis (from 13% to 15%) and headache (occurring more than 7 days after vaccination; 7%e10%). Possibly or probably related AEs were reported by 18%e23% of subjects across groups, with nasopharyngitis being the most frequently related AE reported (5% in the RabiesStandard group, and 4% in the Rabies þ JE-Accelerated group). Seven subjects reported SAEs. For two subjects (both in the Rabies-Standard group), the SAEs were judged as possibly or probably related to the vaccine: one subject had atrial fibrillation on study Day 9, and the other tachycardia and syncope on study Day 10. Both resolved by Day 57. No deaths were reported.
4. Discussion Non-inferiority of antibody responses was demonstrated for the concomitant accelerated (one-week) Rabies þ JE vaccination regimen compared to both the standard rabies (four-week) regimen and the standard Rabies þ JE regimen (four-week). Immune responses to the rabies vaccine were evaluated by measuring RVNA concentrations which, based on previous immunogenicity data, are thought to be the
Table 3
adequate immunogenicity endpoint following rabies immunization, and there is consensus that levels at or above 0.5 IU/mL are protective against rabies [14,15]. In this study, the RFFIT assay, which is the “gold standard” for measuring RVNA concentrations [16], and which is recommended by the WHO [15], was performed at a highly experienced commercial laboratory [13]. As expected, there was a quicker decline in rabies GMCs between Days 15 and 57 in the accelerated regimen group compared to the two standard regimen groups. This is because in the accelerated regimen, the final vaccination was administered on Day 8, whereas in the standard regimens it was administered on Day 29. However, despite differences in short-term antibody kinetics, at Day 57 the vast majority of all subjects (97e100%) had RVNA levels of 0.5 IU/mL. In addition, vaccine tolerability and safety profiles were similar across all groups. The results from the present study also provide support for the use of the standard concomitant Rabies þ JE vaccination regimen; namely, antibody responses to the standard concomitant (Rabies þ JE) regimen were noninferior to those of the standard rabies regimen. GMCs and the percentage of subjects with RVNA concentrations 0.5 IU/mL were similar in both the Rabies þ JE-Standard and the Rabies-Standard groups at all time points from Days 1e57. Moreover, by Day 57, 99% and 100% of subjects in the Rabies-Standard and Rabies þ JE-Standard groups, respectively, were above the antibody level indicative of protection (RVNA 0.5 IU/mL). These finding are consistent with a previous report that concomitant administration of a rabies (Rabipur) and JE (inactivated, mouse-brain derived; Biken) vaccine in toddlers induced adequate and long lasting antibody responses [17]. Vaccine tolerability and safety profiles in the present study were similar for both standard vaccination groups. The ‘0-3-7’ rabies regimen (equivalent to vaccinations on Days 1, 4 and 8 as described in this study) was chosen on the basis that previous studies have demonstrated good immune responses using this regimen [18e20]. Khawplod et al., for example, demonstrated that subjects receiving a shortened pre-exposure rabies vaccination regimen (intramuscular doses on Days 0, 3, and 7) had detectable
Percentage of subjects reporting adverse events (solicited and unsolicited safety sets). Rabies þ JE-Standard N Z 166
Solicted AEs reported from Day 1 to Day 7 (%) Any solicited AEs 83 Local 75 Systemic 60 Other 17 Unsolicited AEs reported from Day 1 to Day 57 (%) Any unsolicited AEs 42 Possibly or probably related AEs 18 AEs leading to premature withdrawal 1 Any SAEs 1 Possibly or probably related SAEs 0
Rabies þ JE-Accelerated N Z 217
Rabies-Standard N Z 220
85 74 66 17
82 73 62 18
50 23 0 1 0
50 22 0 1 1
AE, adverse event; JE, Japanese encephalitis; SAE, serious adverse event. Number of SAEs reported by group: Rabies þ JE Standard: 2 subsects; Rabies þ JE Accelerated: 3 subjects; Rabies standard: 2 subjects.
Accelerated rabies and JE vaccination regimen neutralizing antibody levels one year later [18]. Moreover, Thraenhart and colleagues (among others) have long suggested that the first three vaccinations on Days 0, 3, and 7 for post-exposure prophylaxis are the most important in terms of inducing rapid immunogenicity [20,21]. Likewise, a one-week intradermal regimen for post-exposure rabies prophylaxis (4 doses given on Days 0, 3 and 7) has been shown to be immunogenic with an acceptable safety profile [19]. While the findings in this study are positive, there are a number of limitations to consider. Firstly, since experimental virus challenge is not possible in humans, immunogenicity of the rabies vaccine can only be assessed through surrogate markers. Clearly, surrogate markers are not direct correlates of protection. However, an RVNA level of 0.5 IU/ml has been established as a globally recognized indicator of an adequate response to vaccination against rabies in humans [15,16]. Secondly, the absence of a separate Rabies-Accelerated vaccination group could be considered a potential limitation to this study. The inclusion of such a group might have provided direct evidence to eliminate the possibility that the JE vaccine was serving to boost the immune response to the rabies vaccine. However, this is unlikely since in the present study there was no evidence of this in the standard rabies vaccination group, i.e. the immune responses were very similar in both the Rabies þ JE-Standard and Rabies-Standard groups. Finally, the finding that the accelerated concomitant Rabies þ JE regimen is as effective as the standard rabies regimen only pertains to the short-term period. Long-term data collected at twelve months will be used to determine whether the Rabies þ JE-Accelerated regimen elicits comparable protection to the standard regimen over a longer period. In conclusion, the data from this study demonstrate that a rabies vaccine administered concomitantly with a JE vaccine according to an accelerated (one-week) regimen has a similar short-term immune response and an equally acceptable safety profile to that obtained with either a standard rabies (four-week) or standard combination Rabies þ JE (four-week) regimen. The use of the concomitant regimen is expected to be particularly useful for travelers requiring rabies and JE vaccinations less than one month before travel. Importantly, the immune response to the concomitant Rabies þ JE vaccination regimen (accelerated or standard) was non-inferior to the standard rabies regimen alone. There were also no safety concerns with any vaccination regimen. Ultimately, the possibility of a concomitant (accelerated or standard) Rabies þ JE vaccination regimen offers a convenient and time-saving option particularly suited to short-notice travelers, and should encourage higher numbers to seek out prophylactic protection.
Author contributions TJ, JPC, SD, CH, MP-K, MA, ECR participated in the conduct of the study, data acquisition and interpretation, and contributed to the development of the manuscript. MC participated in the conception, design, statistical analysis, interpretation of analyzed data, and development of the manuscript. DG, DB and ML participated in the conception,
249 design and implementation of the study, interpretation of analyzed data, and development of the manuscript.
Conflicts of interests ML, and MC were full time employees of Novartis group companies at the time of the study, and are now employees of GSK group companies. DB and DG were full-time employees of Novartis Vaccines at the time of the study. TJ was an investigator on the study and received compensation from Novartis Vaccines. MPK accepted fees for speaking and serving on advisory boards and received funding to attend conferences from Baxter, GlaxoSmithKline, Valneva (former Intercell), Novartis and Pfizer. JPC received financial support for conducting this study and has accepted honoraries from Novartis as well as from Valneva/ Intercell for presentations and consulting. CH has received unrestricted educational grants from Novartis, GlaxoSmithKline and Crucell. ECR received financial support for conducting this study and has accepted honoraria from Novartis as well as from Infectopharm, Astellas, Pfizer, Bayer and CureVac for presentations, consulting and travel expenses. SD and MA have no conflicts of interest to disclose.
Funding This study was sponsored by Novartis Vaccines and Diagnostics GmbH.
Acknowledgments The authors would like to thank: All the study participants and Investigators; Kelly Lindert and Ahmed Abdul Mateen for their contribution to the study design; Khaleel Ahmed and Michele Pellegrini for their contribution to study implementation and interpretation of results; and Yvonna Fisher-Jeffes (GlaxoSmithKline LLC, US) and Amanda Prowse (CHC-Europe) for their editorial assistance in the preparation of the manuscript.
References [1] Malerczyk C, Detora L, Gniel D. Imported human rabies cases in Europe, the United States, and Japan, 1990 to 2010. J Travel Med 2011;18:402e7. [2] World Health Organization. International travel and health. Rabies. Available from: http://www.who.int/ith/vaccines/ rabies/en/ [accessed March 2014]. [3] Gautret P, Parola P. Rabies vaccination for international travelers. Vaccine 2012;30:126e33. [4] World Health Organization. International travel and health. Chapter 6. Vaccine-preventable diseases and vaccines 2013 update. Available from: http://www.who.int/ith/chapters/ ith2012en_chap6.pdf?uaZ1 [acessed March 2014]. [5] Altmann M, Parola P, Delmont J, Brouqui P, Gautret P. Knowledge, attitudes, and practices of French travelers from Marseille regarding rabies risk and prevention. J Travel Med 2009;16:107e11. [6] Dolan SB, Jentes ES, Sotir MJ, Han P, Blanton JD, Rao SR, et al. Pre-exposure rabies vaccination among US international
250
[7]
[8]
[9]
[10]
[11]
[12]
[13] [14]
T. Jelinek et al. travelers: findings from the Global TravEpiNet Consortium. Vector Borne Zoonotic Dis 2014;14:160e7. Duffy MR, Reed C, Edelson PJ, Blumensaadt S, Crocker K, Griggs A, et al. A survey of US travelers to Asia to assess compliance with recommendations for the use of Japanese encephalitis vaccine. J Travel Med 2013;20:165e70. Gautret P, Tantawichien T, Vu Hai V, Piyaphanee W. Determinants of pre-exposure rabies vaccination among foreign backpackers in Bangkok, Thailand. Vaccine 2011;29:3931e4. Piyaphanee W, Shantavasinkul P, Phumratanaprapin W, Udomchaisakul P, Wichianprasat P, Benjavongkulchai M, et al. Rabies exposure risk among foreign backpackers in Southeast Asia. Am J Trop Med Hyg 2010;82:1168e71. Van Herck K, Zuckerman J, Castelli F, Van Damme P, Walker E, Steffen R, et al. Travelers’ knowledge, attitudes, and practices on prevention of infectious diseases: results from a pilot study. J Travel Med 2003;10:75e8. Rabipur. Summary of product characteristics. Available from: http://www.eda.mohp.gov.eg/Download/Docs/Files/36_SPC. pdf. [accessed March 2014]. IXIARO. Summary of product characteristics. Available from: http://www.ema.europa.eu/docs/en_GB/document_library/ EPAR_-_Product_Information/human/000963/WC500037287. pdf. [accessed March 2014]. Kansas State University Rabies Laboratory. http://www.vet.kstate.edu/depts/dmp/service/rabies/. Plotkin SA. Correlates of protection induced by vaccination. Clin Vaccine Immunol 2010;17:1055e65.
[15] World Health Organisation. Rabies vaccines. WHO position paper. Wkly Epidemiol Rec (WER) 2010;85:309e20. [16] Moore SM, Hanlon CA. Rabies-specific antibodies: measuring surrogates of protection against a fatal disease. PLoS Negl Trop Dis 2010;4:e595. [17] Pengsaa K, Limkittikul K, Sabchareon A, Ariyasriwatana C, Chanthavanich P, Attanath P, et al. A three-year clinical study on immunogenicity, safety, and booster response of purified chick embryo cell rabies vaccine administered intramuscularly or intradermally to 12- to 18-month-old Thai children, concomitantly with Japanese encephalitis vaccine. Pediatr Infect Dis J 2009;28:335e7. [18] Khawplod P, Wilde H, Benjavongkulchai M, Sriaroon C, Chomchey P. Immunogenicity study of abbreviated rabies preexposure vaccination schedules. J Travel Med 2007;14: 173e6. [19] Shantavasinkul P, Tantawichien T, Wilde H, Sawangvaree A, Kumchat A, Ruksaket N, et al. Postexposure rabies prophylaxis completed in 1 week: preliminary study. Clin Infect Dis 2010; 50:56e60. [20] Thraenhart O, Marcus I, Scheiermann N. 3e1 scheme, a regimen of only two clinic visits with optimal antibody and interferon-induction progress in rabies control. Kent, England: Wells Medical; 1989. p. 536e47. [21] Wilde H, Shantavasinkul P, Hemachudha T, Tepsumethanon V, Lumlertacha B, Wacharapluesadee S, et al. New knowledge and controversies in rabies. J Infect Dis Antimicrob Agents 2009;26:63e74.