Efficacy and Safety of a Tetravalent Dengue Vaccine (TAK-003) in Children With Prior Japanese Encephalitis or Yellow Fever Vaccination

BACKGROUND

We explored the impact of prior Yellow fever (YF) or Japanese encephalitis (JE) vaccination on the efficacy of Takeda's dengue vaccine candidate, TAK-003 (NCT02747927).

METHODS

Children 4-16 years of age were randomized 2:1 to receive TAK-003 or placebo and were under active febrile surveillance. Symptomatic dengue was confirmed by serotype-specific RT-PCR. YF and JE vaccination history was recorded.

RESULTS

Of the 20,071 children who received TAK-003 or placebo, 21.1% had a YF and 23.9% had a JE vaccination history at randomization. Fifty-seven months after vaccination, vaccine efficacy was 55.7% (95% CI, 39.7%-67.5%) in those with YF vaccination, 77.8% (70.8%-83.1%) for JE vaccination, and 53.5% (45.4%-60.4%) for no prior YF/JE vaccination. Regional differences in serotype distribution confound these results. The apparent higher vaccine efficacy in the JE vaccination subgroup could be largely explained by serotype-specific efficacy of TAK-003. Within 28 days of any vaccination, the proportions of participants with serious adverse events in the YF/JE prior vaccination population were comparable between the TAK-003 and placebo groups.

CONCLUSIONS

The available data do not suggest a clinically relevant impact of prior JE or YF vaccination on TAK-003 performance. Overall, TAK-003 was well-tolerated and efficacious in different epidemiological settings.

Long-term efficacy and safety of a tetravalent dengue vaccine (TAK-003): 4·5-year results from a phase 3, randomised, double-blind, placebo-controlled trial

BACKGROUND

About half of the world's population lives in dengue-endemic areas. We aimed to evaluate the long-term efficacy and safety of two doses of the tetravalent dengue vaccine TAK-003 in preventing symptomatic dengue disease of any severity and due to any dengue virus (DENV) serotypes in children and adolescents.

METHODS

In this ongoing double-blind, randomised, placebo-controlled trial, we enrolled healthy participants aged 4-16 years at 26 medical and research centres across eight dengue-endemic countries (Brazil, Colombia, Dominican Republic, Nicaragua, Panama, Philippines, Sri Lanka, and Thailand). The main exclusion criteria were febrile illness (body temperature ≥38°C) at the time of randomisation, hypersensitivity or allergy to any of the vaccine components, pregnancy or breastfeeding, serious chronic or progressive disease, impaired or altered immune function, and previous receipt of a dengue vaccine. Participants were randomly assigned 2:1 (stratified by age and region) using an interactive web response system and dynamic block assignment to receive two subcutaneous doses of TAK-003 or placebo 3 months apart. Investigators, participants, and their parents or legal guardians were blinded to group assignments. Active febrile illness surveillance and RT-PCR testing of febrile illness episodes were performed for identification of virologically confirmed dengue. Efficacy outcomes were assessed in the safety analysis set (all randomly assigned participants who received ≥1 dose) and the per protocol set (all participants who had no major protocol violations), and included cumulative vaccine efficacy from first vaccination to approximately 4·5 years after the second vaccination. Serious adverse events were monitored throughout. This study is registered with ClinicalTrials.gov, NCT02747927.

FINDINGS

Between Sept 7, 2016, and March 31, 2017, 20 099 participants were randomly assigned (TAK-003, n=13 401; placebo, n=6698). 20 071 participants (10 142 [50·5%] males; 9929 [49·5%] females; safety set) received TAK-003 or placebo, with 18 257 (91·0%) completing approximately 4·5 years of follow-up after the second vaccination (TAK-003, 12 177/13 380; placebo, 6080/6687). Overall, 1007 (placebo: 560; TAK-003: 447) of 27 684 febrile illnesses reported were virologically confirmed dengue, with 188 cases (placebo: 142; TAK-003: 46) requiring hospitalisation. Cumulative vaccine efficacy was 61·2% (95% CI 56·0-65·8) against virologically confirmed dengue and 84·1% (77·8-88·6) against hospitalised virologically confirmed dengue; corresponding efficacies were 53·5% (41·6-62·9) and 79·3% (63·5-88·2) in baseline seronegative participants (safety set). In an exploratory analysis, vaccine efficacy was shown against all four serotypes in baseline seropositive participants. In baseline seronegative participants, vaccine efficacy was shown against DENV-1 and DENV-2 but was not observed against DENV-3 and low incidence precluded evaluation against DENV-4. During part 3 of the trial (approximately 22-57 months after the first vaccination), serious adverse events were reported for 664 (5·0%) of 13 380 TAK-003 recipients and 396 (5·9%) of 6687 placebo recipients; 17 deaths (6 in the placebo group and 11 in the TAK-003 group) were reported, none were considered study-vaccine related.

INTERPRETATION

TAK-003 demonstrated long-term efficacy and safety against all four DENV serotypes in previously exposed individuals and against DENV-1 and DENV-2 in dengue-naive individuals.

FUNDING

Takeda Vaccines.

TRANSLATIONS

For the Portuguese, Spanish translations and plain language summary of the abstract see Supplementary Materials section.

Consistency of immunogenicity in three consecutive lots of a tetravalent dengue vaccine candidate (TAK-003): A randomized placebo-controlled trial in US adults

BACKGROUND

We conducted a trial to demonstrate immunogenic equivalence of three consecutive manufacturing lots of Takeda's tetravalent dengue vaccine candidate, TAK-003, and further assessed its safety and reactogenicity.

METHODS

Healthy US adults (n = 923) randomized 2:2:2:1 to four groups received two doses of one of three TAK-003 lots or placebo on Days 0 and 90, with follow-up to Day 270. Primary endpoint evaluated lot-to-lot equivalence of geometric mean neutralizing titers at Day 120 against each of 4 dengue serotypes in baseline seronegative participants. Solicited local and systemic, and unsolicited adverse events (AEs) were assessed for 7, 14 and 28 days after each dose, respectively. Serious AEs (SAE) were monitored throughout the study.

RESULTS

Eight of 12 prespecified equivalence comparisons were met in the per-protocol set but failed marginally in the other 4 mainly due to loss of statistical power following higher than anticipated baseline seropositivity and drop-out rates. All three TAK-003 lots elicited high rates of tetravalent dengue seropositivity (96.7 %, 93.0 % and 97.5 % at Day 120; 91.0 %, 80.5 % and 85.7 % at Day 270) and had similar reactogenicity profiles with no vaccine-related SAEs.

CONCLUSIONS

The three lots of TAK-003 were immunogenic for all four dengue serotypes and well tolerated in healthy adults. Despite not meeting all equivalence comparisons, no major differences were observed between lots and the data support acceptable consistency of the manufacturing process. Trial registrationClinicalTrials.gov identifier: NCT03423173.

An open-label, Phase 3 trial of TAK-003, a live attenuated dengue tetravalent vaccine, in healthy US adults: immunogenicity and safety when administered during the second half of a 24-month shelf-life

Dengue is caused by a mosquito-transmitted flavivirus. The disease is now endemic to many tropical and subtropical regions, manifesting as approximately 96 million symptomatic cases of dengue each year. Clinical trials have shown TAK-003 (Qdenga®), a live attenuated dengue tetravalent vaccine, to be well-tolerated, immunogenic, and efficacious in adults with no prior exposure to dengue virus infection living in non-endemic regions, as well as in adults and children living in dengue-endemic areas. This open-label, single-arm phase 3 trial (NCT03771963) was conducted in two dengue non-endemic areas of the USA, and it evaluated the immunogenicity and safety of naturally-aged TAK-003 administered to adult participants. Overall, the immunogenicity data from this trial are consistent with those reported from other TAK-003 phase 2 and 3 trials, and the safety data are consistent with the broader integrated safety data analysis. The data show that naturally-aged TAK-003 had a well-tolerated reactogenicity and adverse events profile when administered in the second half of its clinical 24-month shelf-life and that it still elicited an immune response that persisted up to 6 months after the second dose against all four dengue serotypes, with no important safety risks identified during the trial.

Bridging the immunogenicity of a tetravalent dengue vaccine (TAK-003) from children and adolescents to adults

Immunobridging is an important methodology that can be used to extrapolate vaccine efficacy estimates to populations not evaluated in clinical studies, and that has been successfully used in developing many vaccines. Dengue, caused by a mosquito-transmitted flavivirus endemic to many tropical and subtropical regions, is traditionally thought of as a pediatric disease but is now a global threat to both children and adults. We bridged immunogenicity data from a phase 3 efficacy study of a tetravalent dengue vaccine (TAK-003), performed in children and adolescents living in endemic areas, with an immunogenicity study in adults in non-endemic areas. Neutralizing antibody responses were comparable in both studies following receipt of a two-dose TAK-003 schedule (months 0 and 3). Similar immune responses were observed across exploratory assessments of additional humoral responses. These data support the potential for clinical efficacy of TAK-003 in adults.

Effect of the Tetravalent Dengue Vaccine TAK-003 on Sequential Episodes of Symptomatic Dengue

In the pivotal phase 3 efficacy trial (NCT02747927) of the TAK-003 dengue vaccine, 5 of 13,380 TAK-003 recipients and 13 of 6,687 placebo recipients experienced two episodes of symptomatic dengue between the first dose and the end of the study, ∼57 months later (patients received the second dose 3 months after the first dose). Two of these participants experienced repeat infection with the same serotype (i.e., homotypic reinfection). In comparison with placebo, the relative risk of a subsequent episode of symptomatic dengue was 0.19 (95% CI, 0.07-0.54) in TAK-003 recipients. Based on the small number of subsequent episodes, these data suggest a potential incremental effect of TAK-003 beyond prevention of the first episode of symptomatic dengue after vaccination.

Efficacy of a Dengue Vaccine Candidate (TAK-003) in Healthy Children and Adolescents 2 Years after Vaccination

BACKGROUND

Takeda's dengue vaccine is under evaluation in an ongoing phase 3 efficacy study; we present a 2-year update.

METHODS

Children (20 099, 4-16 years old) were randomized to receive 2 doses of TAK-003 or placebo 3 months apart and are under surveillance to detect dengue by serotype-specific RT-PCR.

RESULTS

Cumulative efficacy against dengue approximately 27 months since first dose was 72.7% (95% confidence interval [CI], 67.1%-77.3%), including 67.0% (95% CI, 53.6%-76.5%) in dengue-naive and 89.2% (95% CI, 82.4%-93.3%) against hospitalized dengue. In the second year, decline in efficacy was observed (56.2%; 95% CI, 42.3%-66.8%) with the largest decline in 4-5 year olds (24.5%; 95% CI, -34.2% to 57.5%); efficacy was 60.6% (95% CI, 43.8%-72.4%) in 6-11 year and 71.2% (95% CI, 41.0%-85.9%) in 12-16 year age groups. As TAK-003 efficacy varies by serotype, changes in serotype dominance partially contributed to efficacy differences in year-by-year analysis. No related serious adverse events occurred during the second year.

CONCLUSIONS

TAK-003 demonstrated continued benefit independent of baseline serostatus in reducing dengue with some decline in efficacy during the second year. Three-year data will be important to see if efficacy stabilizes or declines further.Clinical Trials Registration. NCT02747927.Takeda's tetravalent dengue vaccine (TAK-003) continued to demonstrate benefit in reducing dengue independent of baseline serostatus up to 2 years after completing vaccination with some decline in efficacy during the second year in 4-16 year olds in dengue-endemic countries.

Three years efficacy and safety of Takeda's dengue vaccine candidate (TAK-003)

Background

Takeda’s live attenuated tetravalent dengue vaccine candidate (TAK-003) is under evaluation in a long-term clinical trial across 8 dengue-endemic countries. Previously, we have reported its efficacy and safety in both seronegative and seropositive participants and that its performance varies by serotype, with some decline in efficacy from first to second year postvaccination. This exploratory analysis provides an update with cumulative and third-year data.

Methods

Healthy 4–16 year olds (n = 20099) were randomized 2:1 to receive TAK-003 or placebo (0, 3 month schedule). The protocol included baseline serostatus testing of all participants and detection of all symptomatic dengue throughout the trial with a serotype specific reverse transcriptase-polymerase chain reaction.

Results

Cumulative efficacy after 3 years was 62.0% (95% confidence interval, 56.6–66.7) against virologically confirmed dengue (VCD) and 83.6% (76.8–88.4) against hospitalized VCD. Efficacy was 54.3% (41.9–64.1) against VCD and 77.1% (58.6–87.3) against hospitalized VCD in baseline seronegatives, and 65.0% (58.9–70.1) against VCD and 86.0% (78.4–91.0) against hospitalized VCD in baseline seropositives. Efficacy against VCD during the third year declined to 44.7% (32.5–54.7), whereas efficacy against hospitalized VCD was sustained at 70.8% (49.6–83.0). Rates of serious adverse events were 2.9% in TAK-003 group and 3.5% in placebo group during the ongoing long-term follow-up (ie, second half of the 3 years following vaccination), but none were related. No important safety risks were identified.

Conclusions

TAK-003 was efficacious against symptomatic dengue over 3 years. Efficacy declined over time but remained robust against hospitalized dengue. A booster dose evaluation is planned.

Immunogenicity and safety of a tetravalent dengue vaccine in dengue-naïve adolescents in Mexico City

Objective.

To describe the immunogenicity and safety of a tetravalent dengue vaccine (TAK-003) in healthy adolescents living in Mexico City, an area considered non-endemic for dengue (NCT03341637).

Methods.

Participants aged 12–17 years were randomized 3:1 to receive two doses (Month 0 and Month 3) of TAK-003 or placebo. Immunogenicity was assessed by microneutralization assay of dengue neutralizing antibodies at baseline, Months 4 and 9. Solicited and unsolicited adverse events (AEs) were recorded after each vaccination. Serious (SAEs) and medically-attended AEs (MAAEs) were recorded throughout the study.

Results.

400 adolescents were enrolled, 391 (97.8%) completed the study. Thirty-six (9%) were baseline seropositive to ≥1 serotypes (reciprocal titer ≥10). Geometric mean titers (GMTs) in baseline seronegative TAK-003 recipients were 328, 1743, 120, and 143 at Month 4, and 135, 741, 46, and 38 at Month 9 against DENV-1, -2, -3, and -4, respectively. Placebo GMTs remained <10. Tetravalent seropositivity rates in vaccine recipients were 99.6% and 85.8% at Months 4 and 9, respectively. One MAAE in each group was considered treatment-related (TAK-003: injection-site erythema, and placebo: pharyngitis).

Conclusion.

TAK-003 was immunogenic against all four serotypes and was well tolerated in dengue-naïve adolescents living in Mexico City.

Efficacy of a tetravalent dengue vaccine in healthy children aged 4-16 years: a randomised, placebo-controlled, phase 3 trial

BACKGROUND

A substantial unmet need remains for safe and effective vaccines against dengue virus disease, particularly for individuals who are dengue-naive and those younger than 9 years. We aimed to assess the efficacy, safety, and immunogenicity of a live attenuated tetravalent dengue vaccine (TAK-003) in healthy children aged 4-16 years.

METHODS

We present data up to 18 months post-vaccination from an ongoing phase 3, randomised, double-blind trial of TAK-003 in endemic regions of Asia and Latin America (26 medical and research centres across Brazil, Colombia, Dominican Republic, Nicaragua, Panama, Philippines, Sri Lanka, and Thailand). Healthy children aged 4-16 years were randomly assigned 2:1 (stratified by age and region) to receive two doses of TAK-003 or two doses of placebo, 3 months apart. Investigators, participants and their parents or guardians, and sponsor representatives advising on trial conduct were masked to trial group assignments. Participants presenting with febrile illness were tested for virologically confirmed dengue (VCD) by serotype-specific RT-PCR. In timeframes beginning 30 days post-second dose, the primary endpoint (overall vaccine efficacy) was assessed in the first 11 months, and the secondary endpoints (efficacy by baseline serostatus, serotype, hospitalised dengue, and severe dengue) in the first 17 months. This study is registered with ClinicalTrials.gov, NCT02747927.

FINDINGS

20 099 participants were randomly assigned and vaccinated between Sept 7, 2016, and Aug 18, 2017; 19 021 (94·6%) were included in the per protocol analysis, and 20 071 (99·9%) in the safety set. The primary endpoint was achieved with an overall vaccine efficacy of 80·2% (95% CI 73·3 to 85·3; 61 cases of VCD in the TAK-003 group vs 149 cases of VCD in the placebo group). In the secondary endpoint assessment timeframe, an overall vaccine efficacy of 73·3% (95% CI 66·5 to 78·8) was observed. Analysis of secondary endpoints showed efficacies of 76·1% (95% CI 68·5 to 81·9) in individuals who were seropositive at baseline, 66·2% (49·1 to 77·5) in individuals who were seronegative at baseline, 90·4% (82·6 to 94·7) against hospitalised dengue, and 85·9% (31·9 to 97·1) against dengue haemorrhagic fever. Efficacy varied by individual serotypes (DENV 1, 69·8% [95% CI 54·8 to 79·9]; DENV 2, 95·1% [89·9 to 97·6]; DENV 3, 48·9% [27·2 to 64·1]; DENV 4, 51·0% [-69·4 to 85·8]). Cumulative rates of serious adverse events were similar in TAK-003 (4·0%) and placebo (4·8%) recipients, and were consistent with expected medical disorders in the study population. Infection was the most frequent reason leading to serious adverse events. 20 participants (<0·1% of the safety set) were withdrawn from the trial due to 21 adverse events by the end of part two; 14 of these participants received TAK-003 and six received placebo.

INTERPRETATION

TAK-003 was well tolerated and efficacious against symptomatic dengue in children regardless of serostatus before immunisation. Vaccine efficacy varied by serotype, warranting continued follow-up to assess longer-term vaccine performance.

FUNDING

Takeda Vaccines.

Efficacy of a Tetravalent Dengue Vaccine in Healthy Children and Adolescents

BACKGROUND

Dengue, a mosquito-borne viral disease, was designated a World Health Organization top 10 threat to global health in 2019.

METHODS

We present primary efficacy data from part 1 of an ongoing phase 3 randomized trial of a tetravalent dengue vaccine candidate (TAK-003) in regions of Asia and Latin America in which the disease is endemic. Healthy children and adolescents 4 to 16 years of age were randomly assigned in a 2:1 ratio (stratified according to age category and region) to receive two doses of vaccine or placebo 3 months apart. Participants presenting with febrile illness were tested for virologically confirmed dengue by serotype-specific reverse-transcriptase polymerase chain reaction. The primary end point was overall vaccine efficacy in preventing virologically confirmed dengue caused by any dengue virus serotype.

RESULTS

Of the 20,071 participants who were given at least one dose of vaccine or placebo (safety population), 19,021 (94.8%) received both injections and were included in the per-protocol analysis. The overall vaccine efficacy in the safety population was 80.9% (95% confidence interval [CI], 75.2 to 85.3; 78 cases per 13,380 [0.5 per 100 person-years] in the vaccine group vs. 199 cases per 6687 [2.5 per 100 person-years] in the placebo group). In the per-protocol analyses, vaccine efficacy was 80.2% (95% CI, 73.3 to 85.3; 61 cases of virologically confirmed dengue in the vaccine group vs. 149 cases in the placebo group), with 95.4% efficacy against dengue leading to hospitalization (95% CI, 88.4 to 98.2; 5 hospitalizations in the vaccine group vs. 53 hospitalizations in the placebo group). Planned exploratory analyses involving the 27.7% of the per-protocol population that was seronegative at baseline showed vaccine efficacy of 74.9% (95% CI, 57.0 to 85.4; 20 cases of virologically confirmed dengue in the vaccine group vs. 39 cases in the placebo group). Efficacy trends varied according to serotype. The incidence of serious adverse events was similar in the vaccine group and placebo group (3.1% and 3.8%, respectively).

CONCLUSIONS

TAK-003 was efficacious against symptomatic dengue in countries in which the disease is endemic. (Funded by Takeda Vaccines; TIDES ClinicalTrials.gov number, NCT02747927.).